One of the biggest additions was the addition of life cycles letting sims could be born, grow up, grow old, and die. And because of this big addition, the crew at Maxis were finally able to create something they've wanted to from the beginning, have sims find their way to college! A while new segment of life called "Young Adulthood" has been added to take advantage of that impressionable age and create the first expansion (there will certainly be more) called The Sims 2 University.
After a teen sim has managed to wade through the confusion of high-school, first loves, and graduation, they can take the option to move off to a university and begin a new section of life. These characters officially become their own family to represent their newfound independence (though they retain the last name and will eventually be able to move back home) and will have to start nearly from scratch. Friends from home can also come to the university, but for the most part, all of your Sims will have to meet and interact with a slew of NPC students.
Each neighborhood in The Sims 2 University will come with a university town associated with it. Sims from different neighborhoods won't be able to go to the same university, but that doesn't mean there won't be plenty of students to interact with at school. On the contrary, there will be plenty of trouble for your budding adults to get into like pranks, parties, frats, sororities, secret societies, cheating, stealing, working... pretty much everything you need as a student. But before any sim can get any of these things, they have to move in...
One thing about going to college is the relative restrictions it will place on an entry year student. If you've been to a university of any sort in real life and lived in the dorms, you'll probably remember that knocking down walls and redesigning was... frowned upon. Such will be the case here. When moving into a dorm, each student will get a private room (noted by the picture of the sim that owns it on the door) which they can decorate with items and wall hangings. No reconstruction allowed. Students will have to wait for any real creative outlet until they move out to other housing.
Source: IGN.COM
