call mark vs pressmark

call mark and pressmark both are nouns.

Word	Noun	Adjective	Verb	Adverb
call mark	Yes	No	No	No
pressmark	Yes	No	No	No

As nouns, call mark and pressmark are synonyms defined as:

call mark and pressmark: a mark consisting of characters written on a book; used to indicate shelf location

Other synonyms of call mark include call number.

call mark (noun)	pressmark (noun)
a mark consisting of characters written on a book; used to indicate shelf location	a mark consisting of characters written on a book; used to indicate shelf location