In obsolete|lang=en terms the difference between obtain and common
is that
obtain is (obsolete) to hold; to keep, possess or occupy while
common is (obsolete) to board together; to eat at a table in common.
As verbs the difference between obtain and common
is that
obtain is to get hold of; to gain possession of, to procure; to acquire, in any way while
common is (obsolete) to communicate (something).
As an adjective common is
mutual; shared by more than one.
As a noun common is
mutual good, shared by more than one.