Not for admission purpose, but for credit purpose it’s important because many SL subjects match AP subjects, and AP will carry credit where SL will not.
No. Their role is different. An AP shows the student can handle rigorous course material and challenges himself or herself. In addition, it allows them to cover a broad base while going in-depth if they really like a subject.
DE however can indicate the student is able to handle more advanced material than AP, especially in sequential fields (ie., Calc BC junior year → Senior Year DE: Multivariable, Discrete Math; or AP Foreign Language junior year → DE Level 4 and 5 or 5 and 6 Senior year).
It also indicates the student is ready for college work - not “college-level”, but actual college work.
APs have 5 class periods a week, hw regulardly scheduled and checked, and cover 1 semester of college material over 10 months. DE classes meet twice or three times a week, require a lot of autonomy and personal work, and cover 1 semester of college material over 4 months.
For adcoms, the best indication of being able to succeed in college classes is previous success in college classes.
For instance, for an advanced student, taking Calculus junior year, then Stats senior year, is a bad move. EITHER take Calc BC senior year and don’t rush, or if you love math take a post-BC class through Running Start/PSEO/DE.
Top colleges consider that 6, 7, 8+ is “most rigorous”. In fact, to them, “most rigorous” does not mean"the most rigorous program a student can physically handle in our school without turning to prescription drugs", but “what the most competitive colleges want to see”. If your GC doesn’t check “most rigorous” for a kid with 7 or 8 APs, the adcoms will smile and think “oh, that insanely competitive school again. Let’s assume this kid has 7 APs… yup… most competitive.” Adcoms aren’t stupid. Just because at some HS a few GCs play games like this doesn’t mean colleges follow suit.