alphabet vs first principles

alphabet and first principles both are nouns.

Word	Noun	Adjective	Verb	Adverb
alphabet	Yes	No	No	No
first principles	Yes	No	No	No

As nouns, alphabet and first principles are synonyms defined as:

alphabet and first principles: the elementary stages of any subject (usually plural)

Other synonyms of alphabet include rudiments.

alphabet (noun)	first principles (noun)
the elementary stages of any subject (usually plural)	the elementary stages of any subject (usually plural)
a character set that includes letters and is used to write a language