Islamism vs Wahhabism

Islamism and Wahhabism both are nouns.

Word	Noun	Adjective	Verb	Adverb
Islamism	Yes	No	No	No
Wahhabism	Yes	No	No	No

As nouns, Wahhabism is a hyponym of Islamism; that is, Wahhabism is a word with a more specific, narrower meaning than Islamism:

Islamism: the monotheistic religious system of Muslims founded in Arabia in the 7th century and based on the teachings of Muhammad as laid down in the Koran
Wahhabism: a conservative and intolerant form of Islam that is practiced in Saudi Arabia

Other hyponyms of Islamism include Mahdism, Salafi movement, Salafism, Shiism, Wahabism, Alawism, Ash'arism.

Islamism (noun)	Wahhabism (noun)
the monotheistic religious system of Muslims founded in Arabia in the 7th century and based on the teachings of Muhammad as laid down in the Koran	a conservative and intolerant form of Islam that is practiced in Saudi Arabia
a fundamentalist Islamic revivalist movement generally characterized by moral conservatism and the literal interpretation of the Koran and the attempt to implement Islamic values in all aspects of life