Two mass generation mechanisms for gauge theories are studied. It is proved that in the abelian case the topological mass generation mechanism introduced in Refs. [4,12,15] is equivalent to the mass generation mechanism defined in Refs. [5,20] with the help of "localization" of a nonlocal gauge invariant action. In the nonabelian case the former mechanism is known to generate a unitary renormalizable quantum field theory describing a massive vector field.PACS numbers: 11.15.q.