When Jesus is saying His Father is ‘greater’ than He is, the God-Man seems to be principally speaking from His man-ward side, for from this ministry His only purpose was to do the will of the Father in all humility and service to mankind. Jesus was not the Father, just as the Spirit is not Jesus, or the Father. They are three distinct persons with the same single divine nature.
Of course Jesus was equal with the Father with respect to his God-ward side, but was made a servant of mankind in his man-ward. The willingness of the Son to perform the work of salvation also indicates the different role that the Son plays in the economy of the Trinity. Although His willing eternal submission may in a sense indicate His role as submissive to the father, even before the incarnation, it does not suggest in the slightest that He does not have absolute equality with the Father. The same can be said of a woman being equal to a man, but the role of the woman is more related to submission than is the man. Persons can be equal and have different roles in their union.
Philippians Chapter 2 gives us a good example of the economy of the Trinity, where the Father often 'wills', the Son 'obeys' and the Spirit 'effectually performs' the work through the Son and to the glory of the Son. The Son by His work glorifies the Father going full circle back to the original purposes of God the Father in Christ made effectual by the Spirit, who finishes and performed the works of Creation through the Father's Word. This is all very clear and settled doctrine.
An true version: (Assuming the Eternal Son is equal with the Father):
Who, being in very nature God, did not consider equality with God something to be used to his own advantage; rather, he made himself nothing by taking the very nature of a servant, being made in human likeness. And being found in appearance as a man,
he humbled himself by becoming obedient to death — even death on a cross! (Philippians 2, 6-8)
This simply means that the Eternal Son who was “in the form of God,” and “equal with God the Father” existing in Eternity in that divine state, and “took on him the” nature and “form of a servant”. He is God by nature, and was incarnate or made flesh by choice. If the father was not a distinct person than when the eternal Son left glory and humbled Himself into the earth, there would be no glory left in heaven, for this glory is the glory of God! If Jesus = the Father, rather than being ‘one with the Father’ this is how I read this verse:
An untrue mangled version of the text (Assuming the Son IS God the Father):
Who, being in very nature the Father, did not consider equality with Himself something to be used to his own advantage; rather, he made himself nothing by taking the very nature of a servant, being made in human likeness. And being found in appearance as a man, he humbled himself by becoming obedient to death — even death on a cross! For his own purposes and will and by His own power never needing to pray to the Father for strength by His Spirit and never needing to be anointed by the Father with the Spirit for this work. (Philippians 2, 6-8 A twisted view)
I think a view that would make any of the three person’s of the Godhead the same would mangle every bible verse related to them as exemplified above. It just does not stand the tests of the scriptures or offer any collective explanation of the many various ways that these three persons in the Godhead are referred to.
I seem to be responding more to Jas31 answer (note: not his real beliefs) than the actually answering the question. I hope this answers both.