advertizement vs ad

advertizement and ad both are nouns.

Word	Noun	Adjective	Verb	Adverb
advertizement	Yes	No	No	No
ad	Yes	No	No	No

As nouns, advertizement and ad are synonyms defined as:

Other synonyms of advertizement include advert, advertisement, advertising, advertizing.

advertizement (noun)	ad (noun)
a public promotion of some product or service	a public promotion of some product or service