moral philosophy vs philosophy

moral philosophy and philosophy both are nouns.

Word	Noun	Adjective	Verb	Adverb
moral philosophy	Yes	No	No	No
philosophy	Yes	No	No	No

As nouns, philosophy is a hypernym of moral philosophy; that is, philosophy is a word with a broader meaning than moral philosophy:

moral philosophy: the philosophical study of moral values and rules
philosophy: the rational investigation of questions about existence and knowledge and ethics

moral philosophy (noun)	philosophy (noun)
the philosophical study of moral values and rules	the rational investigation of questions about existence and knowledge and ethics
	a belief (or system of beliefs) accepted as authoritative by some group or school
	any personal belief about how to live or how to deal with a situation