UC and CSU applications have the applicant self-report courses and grades (to be verified on matriculation with final transcripts).
UC applicants write four essays (chosen from eight possible prompts) in the application. The applicant also lists activities, awards, etc..
CSU applicants do not need to write essays, and have a more limited set of things to add besides their self-reported courses and grades.
Major is relevant to admission selectivity at many campuses.