There are many similarities, though also differences, between an IEP and a 504 https://www.understood.org/en/school-learning/special-services/504-plan/the-difference-between-ieps-and-504-plans
https://schoolpsychologistfiles.com/which-is-better-a-504-plan-or-an-iep/ But, an important issue, IMO, for rising college students, is that an IEP only addresses access to educational services through 12th grade, while accommodations under the 504 rehab act continue into college.