The difference between Wait and Wait upon

When used as verbs, wait means to delay movement or action until the arrival or occurrence of, whereas wait upon means to wait on.

Wait is also noun with the meaning: a delay.

check bellow for the other definitions of Wait and Wait upon

Wait as a verb (transitive, now, rare):

To delay movement or action until the arrival or occurrence of; to await. (Now generally superseded by “wait for”.)
Wait as a verb (intransitive):

To delay movement or action until some event or time; to remain neglected or in readiness.

Examples:

"'Wait here until your car arrives."
Wait as a verb (intransitive, US):

To wait tables; to serve customers in a restaurant or other eating establishment.

Examples:

"She used to wait down at the Dew Drop Inn."
Wait as a verb (transitive, obsolete):

To attend on; to accompany; especially, to attend with ceremony or respect.
Wait as a verb (obsolete):

To attend as a consequence; to follow upon; to accompany.
Wait as a verb (obsolete, colloquial):

To defer or postpone (especially a meal).

Examples:

"to wait dinner"
Wait as a verb (intransitive):

To remain celibate while one's lover is unavailable.

Wait as a noun:

A delay.

Examples:

"I had a very long wait at the airport security check."
Wait as a noun:

An ambush.

Examples:

"They lay in wait for the patrol."
Wait as a noun (obsolete):

One who watches; a watchman.
Wait as a noun (in the plural, obsolete, UK):

Hautboys, or oboes, played by town musicians.

Examples:

"rfquotek Halliwell"
Wait as a noun (in the plural, archaic, UK):

Musicians who sing or play at night or in the early morning, especially at Christmas time; serenaders; musical watchmen. [formerly waites, wayghtes.]

Wait upon as a verb:

To wait on; to serve.

Examples:

"The emperor had dozens of servants to wait upon him."