Oxford and Cambridge are both made up of multiple colleges, and each one of these will have a different location, year group size, facilities, funding availabilities, and there will also be lots of other quirks! All of the 39 colleges here at Oxford are wonderful in their own right, with friendly staff and students, and all sorts of different facilities and things to get involved in. Furthermore, everyone is said to end up loving their college, whether or not they directly applied to it in the first place, so you definitely shouldn't worry about it!
That being said, you can choose a college based on things that are important to you: for example, being close to the department, or being in a college which has a lot of students. At Cambridge, there are a couple of women-only colleges, but at Oxford, all colleges are open to all genders. Some people like being in a college which is very old, whereas others prefer more modern colleges, such as St Catz which is Oxford’s youngest undergraduate college. You might like to be close to the supermarket or the city centre, or you might like to be close to sports grounds. Also, at some colleges, everyone pays the same for accommodation, while at others accommodation is in price bands, so this is also something you might want to consider.
Sometimes people ask whether there are colleges that are 'easier to get into', and the answer to this is no - college choice doesn't make a difference to the chance of you being offered a place. Also, sometimes people apply to a college because a famous lecturer or researcher is a member of that college, however, you might never be taught by them, and often people don't just have their tutorials at the college they're a part of.
Overall, the college you apply to doesn’t really matter too much in the grand scheme of things, and you don’t have complete control over it, so if you’re stressing over which one to choose, you don’t need to! There is plenty of advice on InsideUni, on the rest of the internet, and at Oxford open days to help you decide. You might have interviews at different colleges, or spend your time at Oxford at a college different from the one to which you applied. You can even submit an ‘open application’, where the university allocated you a college for you to be interviewed at, so you don’t have to decide for yourself if you don’t want to.
If you'd like to read what some Cambridge admissions tutors have to say about choosing a college, or what it's like to be pooled or have an open offer, there are blog posts for all of these on our website!