marker vs symbol

marker and symbol both are nouns.

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

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

marker: a distinguishing symbol
symbol: an arbitrary sign (written or printed) that has acquired a conventional significance

marker (noun)	symbol (noun)
some conspicuous object used to distinguish or mark something	something visible that by association or convention represents something else that is invisible
a writing implement for making a mark	an arbitrary sign (written or printed) that has acquired a conventional significance
a distinguishing symbol