problematical vs knotty

problematical and knotty both are adjectives.

Word	Noun	Adjective	Verb	Adverb
problematical	No	Yes	No	No
knotty	No	Yes	No	No

As adjectives, problematical and knotty are synonyms defined as:

problematical and knotty: making great mental demands; hard to comprehend or solve or believe

Other synonyms of problematical include baffling, elusive, problematic, tough.

problematical (adjective)	knotty (adjective)
making great mental demands; hard to comprehend or solve or believe	highly complex or intricate and occasionally devious
open to doubt or debate	used of old persons or old trees; covered with knobs or knots
	making great mental demands; hard to comprehend or solve or believe
	tangled in knots or snarls