There is no difference between the potencies of the arcā and those of the personal forms of the Lord. The example of the postbox and post office may be applied here. The little postboxes distributed all over the city have the same potency as the postal system in general. The duty of the post office is to carry letters from one place to another. If one puts letters in postboxes authorized by the general post office, the function of carrying letters is performed without a doubt. Similarly, the arcā-mūrti can also deliver the same unlimited potency of the Lord as when He is personally present.
(SB 3.1.18p)