如何弄清 "On the top" & "At the top"?

Can you see the difference:
.

Chan is sitting on the top of a table.

The book is ON the top of the bookself. (The book is PHYSICALLY on top of....)
.
.

Chan is AT the top of his class, i.e. he is the number one. (at the top is FIGERATIVE)

Manchester United is positioned at the top of the football leagues.

2006-10-16 13:51:40 補充：
typing error : figurative, not figerative.