lowly vs junior-grade

lowly and junior-grade both are adjectives.

Word	Noun	Adjective	Verb	Adverb
lowly	No	Yes	No	No
junior-grade	No	Yes	No	No

As adjectives, lowly and junior-grade are synonyms defined as:

Other synonyms of lowly include lower-ranking, petty, secondary, subaltern.

lowly (adjective)	junior-grade (adjective)
low or inferior in station or quality	inferior in rank or status
inferior in rank or status
of low birth or station (`base' is archaic in this sense)
used of unskilled work (especially domestic work)