calling vs line of work

calling and line of work both are nouns.

Word	Noun	Adjective	Verb	Adverb
calling	Yes	No	No	No
line of work	Yes	No	No	No

As nouns, line of work is a hypernym of calling; that is, line of work is a word with a broader meaning than calling:

Other hypernyms of calling include business, job, line, occupation.

calling (noun)	line of work (noun)
the particular occupation for which you are trained	the principal activity in your life that you do to earn money