instruction vs subject matter

instruction and subject matter both are nouns.

Word	Noun	Adjective	Verb	Adverb
instruction	Yes	No	No	No
subject matter	Yes	No	No	No

As nouns, subject matter is a hypernym of instruction; that is, subject matter is a word with a broader meaning than instruction:

Other hypernyms of instruction include content, message, substance.

instruction (noun)	subject matter (noun)
the profession of a teacher	content communicating a message; what something is about
the activities of educating or instructing; activities that impart knowledge or skill
(computer science) a line of code written as part of a computer program
a message describing how something is to be done