Ataschasya Swarupeshu Bhedo Gneyo Na Sarvatha - Quite simply, no discrimination should be made between any forms of God here mentioned, as all are forms of Shree Krishna and are the one and the same.
Also the number of arms on a God does not in any way relate to the greatness of that deity, but more so they are forms which devotees have desired to have Darshan of.