我认为前者on有关于的意思
如果指在考试中后者比前者具体
下面供参考
Youwouldusethesentenceintheexambecauseyouareactuallyusingthesentenceintheexamitself.Butwecansaygoodluckontheexamorintheexamaswearen'ttalkingaboutusingluckintheexam,justtheideaasawhole
dowesay''cheatingonexams''or''cheatinginexams''?
Canbeboth,dependsonhowyousayit"Hewascaughtcheatingintheexam"or"Hewascaughtcheatingontheexam".Probably"on"wouldbemorecommonasithasamoredefinitemeaningyouwerecheatingtopasstheexam