at hand vs impending

at hand and impending both are adjectives.

Word	Noun	Adjective	Verb	Adverb
at hand	No	Yes	No	No
impending	No	Yes	No	No

As adjectives, at hand and impending are synonyms defined as:

Other synonyms of at hand include close at hand, imminent, impendent.

at hand (adjective)	impending (adjective)
close in time; about to occur	close in time; about to occur
close in space; within reach