Auditor

In section 140(1), an auditor may be removed before expiry of his term
but in section 140(4), member(s) shall a notice in which (a) A resolution at an AGM appointing as auditor a person other than retiring auditor.
or
(b) A resolution providing expressly that retiring auditor shall not be reappointed

140(1)= Removal before expiry
140(4)= Decision not to reappoint retiring auditor upon expiry of his term except by reason of 139(1).

140(1) is for Removal of Auditor before the expiry of his term only by a special resolution of the company, after obtaining the previous approval of the Central Government.

140(4) is for appointing as auditor a person other than a retiring auditor, or providing expressly that a retiring auditor shall not be re-appointed.