Say you have college A, B and C that are each ranked in the top 100 in the US News or other similar rankings.
Admissions (SAT scores, GPA, et cetera) standards, quantitatively, rank A>B>C as the hardest and the easiest of the three to get into.
It's clear that college A has the 'best' students according to the metrics the entrance standards measure. It could measure IQ (SAT), effort and communication skills and critical thinking skills (GPA).
Would you say, in mathematics and elsewhere, that the content of the material is markedly different? For instance, could the undergraduate textbooks used be different?
In the end, why do students from prestigious colleges have such a leg up in terms of finding jobs and getting into graduate schools of similar prestige, if the material taught is similar, in terms of the amount of material taught and the difficulty of the exams?