However, they would be comparing lower level courses at their old colleges to upper level courses at their new colleges.
Some might also ask graduate students to compare their undergraduate and graduate schools, but it may not be the best comparison to ask (for example) a chemistry PhD student how difficult general chemistry was at his/her undergraduate school when s/he was learning it the first time versus at his/her graduate school when s/he was TAing it after spending a few years studying chemistry.