experiment vs research project

experiment and research project both are nouns.

Word	Noun	Adjective	Verb	Adverb
experiment	Yes	No	Yes	No
research project	Yes	No	No	No

As nouns, research project is a hypernym of experiment; that is, research project is a word with a broader meaning than experiment:

experiment: the act of conducting a controlled test or investigation
research project: research into questions posed by scientific theories and hypotheses

Other hypernyms of experiment include scientific research.

experiment (noun)	research project (noun)
the act of conducting a controlled test or investigation	research into questions posed by scientific theories and hypotheses
a venture at something new or different
the testing of an idea

experiment (verb)	research project (verb)
to conduct a test or investigation
try something new, as in order to gain experience