sympathizer vs sympathiser

sympathizer and sympathiser both are nouns.

Word	Noun	Adjective	Verb	Adverb
sympathizer	Yes	No	No	No
sympathiser	Yes	No	No	No

As nouns, sympathizer and sympathiser are synonyms defined as:

sympathizer and sympathiser: someone who shares your feelings or opinions and hopes that you will be successful

Other synonyms of sympathizer include well-wisher.

As nouns, sympathizer and sympathiser are synonyms defined as:

sympathizer and sympathiser: a person who commiserates with someone who has had misfortune

Other synonyms of sympathizer include comforter.

sympathizer (noun)	sympathiser (noun)
someone who shares your feelings or opinions and hopes that you will be successful	someone who shares your feelings or opinions and hopes that you will be successful
a person who commiserates with someone who has had misfortune	a person who commiserates with someone who has had misfortune