widening vs increment

widening and increment both are nouns.

Word	Noun	Adjective	Verb	Adverb
widening	Yes	No	No	No
increment	Yes	No	No	No

As nouns, increment is a hypernym of widening; that is, increment is a word with a broader meaning than widening:

widening: an increase in width
increment: a process of becoming larger or longer or more numerous or more important

Other hypernyms of widening include growth, increase.

widening (noun)	increment (noun)
the act of making something wider	the amount by which something increases
a part of a road that has been widened to allow cars to pass or park	a process of becoming larger or longer or more numerous or more important
an increase in width