behind-the-scenes vs under-the-table

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

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

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

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

Other synonyms of behind-the-scenes include sub-rosa.

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