protracted vs lengthy

protracted and lengthy both are adjectives.

Word	Noun	Adjective	Verb	Adverb
protracted	No	Yes	No	No
lengthy	No	Yes	No	No

As adjectives, protracted and lengthy are synonyms defined as:

protracted and lengthy: relatively long in duration; tediously protracted

Other synonyms of protracted include drawn-out, extended, prolonged.

protracted (adjective)	lengthy (adjective)
relatively long in duration; tediously protracted	relatively long in duration; tediously protracted