Abstruse means complex, deep, or difficult to understand. (see also: Recondite vs Abstruse vs Occult vs Esoteric )
- To the average person, Einstein’s theory of relativity is abstruse.
Obtuse means dull witted, not too sharp, or slow to understand. (see also: Dull vs Blunt vs Obtuse )
- Sorry if I’m being obtuse, but I do not understand the point.