elongation vs improver

elongation and improver both are nouns.

Word	Noun	Adjective	Verb	Adverb
elongation	Yes	No	No	No
improver	Yes	No	No	No

As nouns, improver is a hypernym of elongation; that is, improver is a word with a broader meaning than elongation:

Other hypernyms of elongation include add-on, addition.

elongation (noun)	improver (noun)
the act of lengthening something	a component that is added to something to improve it
an addition to the length of something	someone devoted to the promotion of human welfare and to social reforms
the quality of being elongated