soccer vs association football

soccer and association football both are nouns.

Word	Noun	Adjective	Verb	Adverb
soccer	Yes	No	No	No
association football	Yes	No	No	No

As nouns, soccer and association football are synonyms defined as:

soccer and association football: a football game in which two teams of 11 players try to kick or head a ball into the opponents' goal

soccer (noun)	association football (noun)
a football game in which two teams of 11 players try to kick or head a ball into the opponents' goal	a football game in which two teams of 11 players try to kick or head a ball into the opponents' goal