They are comparable in that they are both an increasing exercise of power wrt what had been previously done.

I concur with GP; you are arriving at the conclusion through your own logic but somehow not seeing the conclusion. See intermerda's point below.

You really can't see how they are both powers that presidents (arguably) technically have but which they do not execute? And that a president actually exercising such a power is thus a power grab?

Nothing in my comment is comparing them or suggesting they are comparable.