pressmark vs call mark

pressmark and call mark both are nouns.

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

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

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

Other synonyms of pressmark include call number.

pressmark (noun)	call mark (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