At the 2 schools I mentioned previously, students have to submit an additional application in order to join the honors college. Requires 1 or 2 letters of rec, a separate personal statement, and an activities list/resume/whatever you call it. Then it goes through a “holistic review” and you’re notified later on of your honors college admissions status.
Remaining in the honors college requires maintaining a certain min GPA. Students also need to take a certain # of honors units by the time they graduate. Again, for the 2 colleges is mentioned, it also requires completion of a special senior project.
Honors students get priority registration, meaning they sign up for classes at same time the seniors do. ASU and UofA both have honors-only dorms with attached dining halls that only honors students can use (I take that back…reg ASU students can use the honors dining hall but it costs them extra).
Both honors complexes/dorms/buildings also have honors class professors’ offices on first floor. Plus some classrooms so a lot of freshman honors seminar classes are basically right downstairs from where you live. And the honors college admin and honors-only advisors are also on the first floor.
Both schools have additional special programs which only honors students can take advantage of, like special study abroad options, special access to internships and research with professors, etc.
Your mileage may vary at other schools, of course.