under-the-table vs behind-the-scenes

under-the-table and behind-the-scenes both are adjectives.

Word	Noun	Adjective	Verb	Adverb
under-the-table	No	Yes	No	No
behind-the-scenes	No	Yes	No	No

As adjectives, under-the-table and behind-the-scenes are synonyms defined as:

under-the-table and behind-the-scenes: designed and carried out secretly or confidentially

Other synonyms of under-the-table include sub-rosa.

under-the-table (adjective)	behind-the-scenes (adjective)
designed and carried out secretly or confidentially	designed and carried out secretly or confidentially