primarily vs principally

primarily and principally both are adverbs.

Word	Noun	Adjective	Verb	Adverb
primarily	No	No	No	Yes
principally	No	No	No	Yes

As adverbs, primarily and principally are synonyms defined as:

Other synonyms of primarily include chiefly, in the main, mainly.

primarily (adverb)	principally (adverb)
of primary import	for the most part
for the most part