What's the lingual difference between "On" , "Above" , "Over" , "Upon" ??

Answer 1

Physical senses:
On - sitting atop (implies physically touching)
Upon - same as "on"
Above - hovering over (implies not touching, as perhaps flying over, not necessarily directly above, but somewhere higher than, in elevation)
Over - same as Above

Non-physical senses
On - at, as in at the point of, as in "on rising, I shall brush my teeth"
Above - beyond, as in "above all, I intend to have happiness"
Over - at the end, as in "the party's over"
Upon - bearing or depending, as in "the responsibility for this interpretation is upon you"

...There are other meanings for these words, as well...the English language is too darned complex to outline them all, so fetch yourself a good dictionary to see some (not necessarily all) of them...

Answer 2

Are you near a table? Place your hand, palm down in such a way that your palm is in contact with the top of the table. Your hand is "on the table" or "upon the table." Now, raise your hand about six inches. Your hand is "above" or "over" the table.

Answer 3

Try "dictionary.com" or look it up in a style manual.