shadow vs overtop

shadow is a noun but overtop is not a noun.

Word	Noun	Adjective	Verb	Adverb
shadow	Yes	No	Yes	No
overtop	No	No	Yes	No

As verbs, overtop is a hypernym of shadow; that is, overtop is a word with a broader meaning than shadow:

Other hypernyms of shadow include command, dominate, overlook.

shadow (noun)	overtop (noun)
refuge from danger or observation
something existing in perception only
an indication that something has been present
a premonition of something adverse
an unilluminated area
a spy employed to follow someone and report their movements
an inseparable companion
a dominating and pervasive presence
shade within clear boundaries

shadow (verb)	overtop (verb)
follow, usually without the person's knowledge	look down on
make appear small by comparison
cast a shadow over