marker vs bookmarker

marker and bookmarker both are nouns.

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

As nouns, bookmarker is a hyponym of marker; that is, bookmarker is a word with a more specific, narrower meaning than marker:

marker: some conspicuous object used to distinguish or mark something
bookmarker: a marker (a piece of paper or ribbon) placed between the pages of a book to mark the reader's place

Other hyponyms of marker include bookmark, yard marker.

marker (noun)	bookmarker (noun)
some conspicuous object used to distinguish or mark something	a marker (a piece of paper or ribbon) placed between the pages of a book to mark the reader's place
a writing implement for making a mark
a distinguishing symbol