authorship vs penning

authorship and penning both are nouns.

Word	Noun	Adjective	Verb	Adverb
authorship	Yes	No	No	No
penning	Yes	No	No	No

As nouns, authorship and penning are synonyms defined as:

Other synonyms of authorship include composition, writing.

authorship (noun)	penning (noun)
the act of creating written works	the act of creating written works
the act of initiating a new idea or theory or writing