gatecrasher vs unwelcome guest

gatecrasher and unwelcome guest both are nouns.

Word	Noun	Adjective	Verb	Adverb
gatecrasher	Yes	No	No	No
unwelcome guest	Yes	No	No	No

As nouns, gatecrasher and unwelcome guest are synonyms defined as:

gatecrasher and unwelcome guest: someone who gets in (to a party) without an invitation or without paying

Other synonyms of gatecrasher include crasher.

gatecrasher (noun)	unwelcome guest (noun)
someone who gets in (to a party) without an invitation or without paying	someone who gets in (to a party) without an invitation or without paying