dollar vs symbol

dollar and symbol both are nouns.

Word	Noun	Adjective	Verb	Adverb
dollar	Yes	No	No	No
symbol	Yes	No	No	No

As nouns, symbol is a hypernym of dollar; that is, symbol is a word with a broader meaning than dollar:

dollar: a symbol of commercialism or greed
symbol: an arbitrary sign (written or printed) that has acquired a conventional significance

dollar (noun)	symbol (noun)
a symbol of commercialism or greed	something visible that by association or convention represents something else that is invisible
a piece of paper money worth one dollar	an arbitrary sign (written or printed) that has acquired a conventional significance
a United States coin worth one dollar
the basic monetary unit in many countries; equal to 100 cents