school of thought vs philosophical system

school of thought and philosophical system both are nouns.

Word	Noun	Adjective	Verb	Adverb
school of thought	Yes	No	No	No
philosophical system	Yes	No	No	No

As nouns, school of thought and philosophical system are synonyms defined as:

school of thought and philosophical system: a belief (or system of beliefs) accepted as authoritative by some group or school

Other synonyms of school of thought include doctrine, ism, philosophy.

school of thought (noun)	philosophical system (noun)
a belief (or system of beliefs) accepted as authoritative by some group or school	a belief (or system of beliefs) accepted as authoritative by some group or school