Islamism vs Salafism

Islamism and Salafism both are nouns.

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

As nouns, Salafism is a hyponym of Islamism; that is, Salafism 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
Salafism: a militant group of extremist Sunnis who believe themselves the only correct interpreters of the Koran and consider moderate Muslims to be infidels; seek to convert all Muslims and to insure that its own fundamentalist version of Islam will dominate the world

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

Islamism (noun)	Salafism (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 militant group of extremist Sunnis who believe themselves the only correct interpreters of the Koran and consider moderate Muslims to be infidels; seek to convert all Muslims and to insure that its own fundamentalist version of Islam will dominate the world
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