Students are very friendly and helpful on campus and in class. Columbia definitely has its share of cut-throat competitive students, but for the most part students are willing to help other students and love to work in groups to lessen their load and feed off each other's information and knowledge.
While I do know personally of 2 students who have had a bad experience/confrontation with another student in the context of race, religion, or another classification/belief, student to student direct issues are not a problem. There have, however, been multiple instances of bias and hate crimes at Columbia University as a whole, but in the fashion of crude writings on walls or other public displays of hate, never violence. The students here are very passionate about their beliefs which can be great or can be awful when those beliefs are unfounded and hurtful to others.
Because Columbia is in the heart of New York city, the atmosphere is just as fast paced. I think that students from slower paced lifestyles, such as from the South or California, might feel out of place or overwhelmed and not used to city life. But there are definitely people from both areas who need to be here in order to remind everyone to chill out sometimes. Republicans may also feel out of place due to the extremely liberal city and campus, but they can join the College Republicans if they are in need of some solidarity.
Again I stress that this is New York City, so the lifestyle is not as relaxed as elsewhere. In terms of fashion, students definitely know how to dress well. People take pride in their appearance on a daily basis in or out of class. Some people feel the need to take it to the next level, and some feel more comfortable rolling out of bed and going to class. I'd say its good to have a mixture of both to keep your sanity; respect yourself and take pride in your appearance, but wear a t-shirt and sweats whenever you don't feel like caring, no one will fault you for it, especially in a 9am class.
The four main student types are SEAS, Stereotypical Ivy, Athlete, and More Relaxed. The SEAS students, who are typically Asian or Indian, are usually the ones in the library late at night, reading as they eat, and extremely stressed about classes. The Stereotypical Ivy Leaguers are the pretentious, competitive ones who either come from money or want people to think they come from money, and are really stressed about their future of making more money. The Athletes are dedicated to their sport, eat a lot to boost energy, loud and fun, but stressed out balancing practice and a full course load. The More Relaxed crowd is made up of the Frats and Sororities, Black and Hispanic students, Theater kids, and all others who aren't loners. The Greek students actually have a social life, the Black and Hispanic students are always full of life, loud, energetic, and know how to work hard and still have fun, the Theater kids are off being talented and artsy, and all of them combined with the others who are not loners are all stressed out because they are Columbia Students. (The loners aren't a separate type because there are few of them, but they're usually in SEAS)
A lot of students are from the greater NY area. I here a lot of people say they're from Maryland, Massachusetts, Texas and the South, Midwest and California, and internationally from China, Korea, India, Europe, and the Caribbean Islands. I would guess that the majority of students are on Financia Aid or have some sort of grant or scholarship. Just in my group of friends theres one who struggles a lot with money, a few that somewhat struggle with money, a few that don't worry about money and are comfortable, and one that spends money like there's no tomorrow and can afford to do so. Even with such diverse backgrounds, most people are politically aware, and even international students are very aware of American politics, sometimes more so than American students.