illusion vs head game

illusion and head game both are nouns.

Word	Noun	Adjective	Verb	Adverb
illusion	Yes	No	No	No
head game	Yes	No	No	No

As nouns, illusion and head game are synonyms defined as:

illusion and head game: the act of deluding; deception by creating illusory ideas

Other synonyms of illusion include delusion.

illusion (noun)	head game (noun)
the act of deluding; deception by creating illusory ideas	the act of deluding; deception by creating illusory ideas
an illusory feat; considered magical by naive observers
something many people believe that is false
an erroneous mental representation