What's the Difference Between Sunscreen and Sunblock?

As a former food writer, I have a complicated relationship with seasonality. When you’re banned from writing about tomatoes and eggplant and corn outside the hours of late July to early September, you know what you want to do? You wanna write about tomatoes in December. 

So with What’s the Difference, we’re deciding that seasonality is a construct. (Unless it serves the purpose of a cute newsletter introduction—in that case, we love the seasons.) And unlike tomatoes in December, which are objectively gross, sunscreen and sunblock should be worn year-round! But before we get to skincare tips, let’s dig into the difference.

Sunscreen is a lotion that absorbs the sun’s ultraviolet (UV) rays; it contains chemicals that soak them up before they reach the skin. It’s therefore referred to as a chemical sunscreen. Sunscreens can have a wide range of active ingredients, but the good ones contain benzophenones, which protect against UVA rays (the ones that cause premature aging and wrinkling), and cinnamates and/or salicylates, which protect against UVB rays (the ones that cause sunburns). 

Sunblock, on the other hand, reflects the sun’s rays from the skin instead of absorbing them. It’s therefore thought of as a physical sunscreen. Sunblock is usually thicker and more opaque than sunscreen, and it can sometimes leave behind white residue. And although it’s heavier, sunblock’s active ingredients—titanium dioxide or zinc oxide—are gentler, making it a safer choice for people who have sensitive skin.

Dermatologists say that unless you have a personal preference, both sunscreen and sunblock are fine to use—one’s not better than the other. However, whatever you choose should have an SPF of at least 30 and protect against both UVA and UVB rays; if you see the term “broad spectrum” on the label, you’re good to go. And make sure to avoid suntan lotion, which is a different product altogether; it usually has an SPF of 15 or lower, and is made with oils that don’t protect your skin at all. You might want that sun-kissed look, but safety comes first—no matter what season it is.

If you liked this, subscribe to the What's the Difference newsletter here! 

What's the Difference Between Pottery and Ceramics?

Chances are, you used some sort of pottery/ceramic product today: the mug you drank your coffee out of, the plate you ate your lunch on, the artisanal, hand-made pot you warmed your artisanal, stone-ground oats in, etc. But do you ever stare at the mountain of dishes in your sink and ask yourself, Gee, would those be classified as pottery or ceramics?No? Well, you’re about to learn the difference anyways.  

Technically speaking, ceramics are things made from non-metal materials that are permanently changed when they’re heated. The classic example is clay: even a dried clay product will disintegrate in water, but once it’s heated to between 350°C and 800°C (or above), it can get as wet as you want it. Glazes, which are actually a type of glass, are also ceramic; the firing process makes them stiffer than glass that’s poured or blown, allowing them to stick to clay surfaces. Other ceramic materials include the stuff that’s used in industrial or “advanced” ceramics, like silica carbide and zirconium oxide; these are the materials that things like spaceships are made of, and they're able to withstand the super-hot temperatures generated upon re-entering the earth’s atmosphere. 

Pottery is a type of ceramic, specifically containers made out of clay. (So an art piece made out of clay would not be pottery—it’d just be ceramics.) There are three major categories of pottery: earthenware, stoneware, and porcelain. 

Earthenware is made of clay that’s fired at relatively low temperatures (1,000°C to 1,150°C). The resulting product is porous and coarse, which then gets glazed and fired a second time. 

Stoneware is made of clay that’s fired at a high temperature (1,200°C) until it’s the consistency of glass, a process called vitrification. Because stoneware is non-porous, any glaze applied to it is purely decorative. 

Porcelain is a very hard, translucent white ceramic. To make it, small amounts of glass, granite, and feldspar minerals are ground up with fine, white clay and then mixed with water until the mixture is malleable. The resulting products get fired between 1,200°C and 1,450°C; decorated with glaze; and then fired again. This is also known as fine china. Bone china, which is stronger than porcelain, is made by mixing feldspar minerals, fine silica sand, and ash from cattle bones into that fine, white clay, and then is shaped and fired in the same manner. 

If you liked this, subscribe to the What's the Difference newsletter here! 

What's the Difference Between Cement and Concrete?

While commuting to work in a place such as, say, New York City, one might find oneself taking in the landscape’s natural beauty: the scent of hot garbage wafting through the air, the wail of various sirens, the odd substances crusting and pooling on the sidewalk. One might ask oneself, Why didn’t I pursue a career as a ski instructor? Also, is this sidewalk made of cement or concrete? And that’s when a weekly What’s the Difference email, and its focused desire to turn the splitting of hairs into a little bit of delight, makes the commute a little more bearable.

Because it turns out, cement and concrete are two very different things. Cement is a powdery substance made up of limestone, sand, clay, bauxite, and/or iron ore, and sometimes includes materials like shells, chalk, marl, shale, blast furnace slag, fly ash, and/or slate. (Some of these “cementitious materials” are actually similar to the volcanic ashes the ancient Romans used to build the Colosseum!) The process of making cement is actually pretty cool: raw materials like limestone and clay are quarried, then crushed into pieces around 3 inches or smaller. The crushed rock is then combined with iron ore or fly ash; ground into even smaller pieces; and then fed into a cement kiln, which has a diameter of 12 feet and, in many cases, is longer than the height of a 40-story building. The high temperatures in the kiln unite the particles into a new substance called clinker, which comes out red-hot in balls the size of marbles. The clinker is cooled in special coolers, then ground into a powder. The resulting cement is so fine that it can pass through a sieve capable of holding water; one pound of cement contains 150 billion grains.

So if cement is a powder, what’s concrete? Concrete is a mixture of sand, gravel, and/or crushed stone (known as “aggregates”) and a paste made of water and—wait for it—CEMENT. This water-cement paste (also used in mortar for brick-laying) coats the sand, gravel, and stone and binds them all together. Through a chemical process called hydration, the paste hardens and gains strength over time; over 90% of a concrete mix’s strength will be reached within four weeks, with the remaining 10% accumulating over decades. Typically, a mix of concrete will contain 10–15% cement, 60–70% aggregates, and 15–20% water, with air bubbles sometimes making up another 5–8%. That concrete is used to build everything from skyscrapers to streets, houses to highways—and probably the very sidewalk you walked down today.

If you liked this, subscribe to the What's the Difference newsletter here! 

What's the Difference Between Trash and Garbage?

If you subscribe to this newsletter, you probably love to learn. You’re definitely smart. And you, like me, probably spend approximately zero time thinking about the difference between trash and garbage. Whatever—it’s just stuff you throw out! 

But this newsletter is here to make life a little more exciting, and what’s more exciting than taking the things we deal with every day—like trash and garbage—and becoming more informed about them?? Right?? 

So to answer one of life’s most pressing questions: YES, there is a difference between trash and garbage. Garbage is made up of stuff that comes from the bathroom or kitchen—think moldy bread, gnawed-on chicken wings, used paper towels, empty bags of potato chips and peanut M&Ms. Trash, on the other hand, is everything else: broken furniture, old tires, boxes of stuff collecting dust in the attic, President Trump, etc.

And remember: don’t forget to recycle!

If you liked this, subscribe to the What's the Difference newsletter here!