On-Upon | Commonly Confused Words

Upon

/ə'pɔn/

Shows something happening because of or immediately after an event or action

All gaze upon him, and all do him honour.But yestermorn I turned my back upon it;'The sins of the fathers will be visited upon the children.'

/ɒn/

Indicating a position touching or in contact with the surface of a place or object

I think the wallet is on the table.From then on she took control of everything.He turned and put his hand on Silver Blaze is back.

This word has no antonyms

On is a more general term used to indicate position or necessity and is often used in everyday expressions.
Upon is a more formal or literary synonym for on, often used in storytelling or legal documents.
On is commonly used in modern speech while upon often appears in phrases that are considered more traditional or poetic.
Remember, on implies a direct position on a surface, whereas upon can imply moving to a position on a surface.
Upon may sometimes convey a sense of immediacy or suddenness which on does not.