There are a lot of things that are different from the United States, like the obvious (language and food) to little things one almost overlooks. Here are some of both I've noticed:
1. The language. Obviously they speak Spanish here, since I'm in Spain. But the region I'm in has a second official language: Gallego. Many of the street signs, newspapers, and books are in Gallego. Fortunately there are several cognates from Gallego to Spanish so it's easy to guess what the sign, etc., means.
2. The meals/food. Probably the biggest thing after the language that I have slightly adjusted to is the food and times of meals. Everything is fresher here. The dishes my host mom makes are different from at home only in the way they are prepared; they use the same ingredients and it's pretty delicious just the same. The super strange thing is when they eat meals. Breakfast is normal, between the time you wake up and leave for work/school, but lunch is anywhere between 2 and 3:30. Many stores close and students finish class at 2 so everyone goes home for lunch. Stores reopen around 4 and stay open until 8:30. This time in between is called siesta, and it's ideal for taking naps :) Then supper is eaten between 9 and 10 at night. This is the weirdest thing, especially because once supper is over it feels too late to hang out with friends but too early to go to bed. So I usually talk to my host mom about different cultural things or email friends from home.
3. Smoking. Unlike in the US, it's legal to smoke outside, and it seems like everyone does it.
4. The dogs. Similar to smoking, it seems like everyone here has a dog and they walk them everywhere. They come in a variety of sizes, from German Shepherds to terriers, but they are all extremely well-behaved; some aren't even on leashes and still follow their owners. My dog could use some European training ;)
5. Water. They don't have hot water here except in the shower because it's expensive. This was a shock and I don't know if I'll get used to it. But because it's expensive, we're not supposed to spend a lot of time in the shower anyway. I'm starting to realize how spoiled Americans are hahaha
6. Clothing. Spaniards are very stylish. They wear everyday what I wear to dress up. This means I had to buy a few more dressy clothes before coming here so that I would fit in. (I think I've done a pretty good job so far; three or four people have come up to me asking for directions, thinking I was a native. Success!) Almost everyone wears boots or Converse, and skinny jeans (even the men). It's nice to dress up every once in a while, but some days I want to be really messy and just throw on a hooded sweatshirt. However, that would be like a neon sign shouting "American!", so I can only wear it in the apartment *sigh*
7. Affection. Couples are unafraid to let everyone know how much they care for their significant other. Hand holding, quick pecks on the lips, and sometimes even full on making out is common in restaurants and in other public places. This will also take some getting used to, but I'm not alone in my discomfort. Other Americans here whisper to each other, "Did you see what they're doing over there? She's sitting on his lap! This is so awkward..."
8. Walking. People in Santiago walk everywhere, and slowly, which is the most frustrating. I usually just walk around them, even though it probably distinguishes me as a non-local.
9. Military time. They use military time here, which wasn't too challenging to get the hang of once you memorize that 16:00 is 4pm, 20:00 is 8pm, etc, etc.
Of course there are many other things I could mention, but these are just a few to give you a taste of how I'm living right now. Nothing so major that I can't adjust; it's actually kind of fun experiencing life at a different pace. I'm working on more posts on what I did during the first week here (including celebrate my birthday!) and also trying to figure out how to post pictures, so you'll be hearing from me again soon.
Ciao!