bookmark vs bookmarker

bookmark and bookmarker both are nouns.

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

As nouns, bookmark and bookmarker are synonyms defined as:

bookmark and bookmarker: a marker (a piece of paper or ribbon) placed between the pages of a book to mark the reader's place

bookmark (noun)	bookmarker (noun)
a marker (a piece of paper or ribbon) placed between the pages of a book to mark the reader's place	a marker (a piece of paper or ribbon) placed between the pages of a book to mark the reader's place