on the Q.T. vs in secret

on the Q.T. and in secret both are adverbs.

Word	Noun	Adjective	Verb	Adverb
on the Q.T.	No	No	No	Yes
in secret	No	No	No	Yes

As adverbs, on the Q.T. and in secret are synonyms defined as:

Other synonyms of on the Q.T. include on the QT, secretly.

on the Q.T. (adverb)	in secret (adverb)
in secrecy; not openly	in secrecy; not openly