obstacle vs obstructer

obstacle and obstructer both are nouns.

Word	Noun	Adjective	Verb	Adverb
obstacle	Yes	No	No	No
obstructer	Yes	No	No	No

As nouns, obstructer is a hypernym of obstacle; that is, obstructer is a word with a broader meaning than obstacle:

obstacle: an obstruction that stands in the way (and must be removed or surmounted or circumvented)
obstructer: any structure that makes progress difficult

Other hypernyms of obstacle include impediment, impedimenta, obstruction, obstructor.

obstacle (noun)	obstructer (noun)
an obstruction that stands in the way (and must be removed or surmounted or circumvented)	any structure that makes progress difficult
something immaterial that stands in the way and must be circumvented or surmounted	someone who systematically obstructs some action that others want to take