In obsolete|lang=en terms the difference between scan and oversee
is that
scan is (obsolete) to mount by steps; to go through with step by step while
oversee is (obsolete) to fail to see; to overlook, ignore.
As verbs the difference between scan and oversee
is that
scan is to examine sequentially, part by part while
oversee is (literally) to survey, look at something in a wide angle.
As a noun scan
is an instance of scanning.