ramjet vs jet engine

ramjet and jet engine both are nouns.

Word	Noun	Adjective	Verb	Adverb
ramjet	Yes	No	No	No
jet engine	Yes	No	No	No

As nouns, jet engine is a hypernym of ramjet; that is, jet engine is a word with a broader meaning than ramjet:

ramjet: a simple type of jet engine; must be launched at high speed
jet engine: a gas turbine produces a stream of hot gas that propels a jet plane by reaction propulsion

ramjet (noun)	jet engine (noun)
a simple type of jet engine; must be launched at high speed	a gas turbine produces a stream of hot gas that propels a jet plane by reaction propulsion