After spending a decade or so in prison (context), where he arose as temporal and spiritual leader of the ‘local’ population, Yosef (Joseph) finds himself, through a truly fantastic chain of events (context), appointed by the Pharaoh–effective ruler of Egypt, which was all ready by then the most important empire in the world (it was, then, soon to become ever more wealthy and powerful, see the above link).
The definition of Yosef’s power and position is, in the words of the Pharaoh. “without you[r permission], no man shall lift his hand nor foot, in the entire land of Egypt.”(Genesis 41:44); “By your word my nation shall be sustained; only by my throne, shall I be greater than you; [they shall call me King, comments Rashi], (ibid 41:40).
Pharaoh sets forth his reasoning, thusly, “Can there be found [anywhere] a man like this, in whom is found the spirit of G-d?!”; “as G-d has revealed to you all this, there is no understanding and wise [man] like you.” (ibid 41:38; 41;39).
For Yosef’s inauguration, the Pharaoh parades Yosef in the chariot designated second to the king’s own, while criers call out, referring to Yosef, the title “Avrech”.
The title “Avrech”, a word etymologically derived from the Hebrew “Verech” (knee), was designed to convey how all Egyptians were to kneel before Yosef. (Physical attestations of subjugation were the norm then, as is well known.)
Interestingly though, later on, after many years, when the children of Jacob (Israel)–coming as they were from Cana’an to purchase direly needed food and not being able to recognize Yosef, their brother, by sight–appear before Yosef, they prostrate themselves before him, “faces to the ground”.
But the custom was to kneel?
The resolution is simple: Egyptians, understanding that Yosef’s power was (then) not fully his own, but rather an extension of the will of the Pharaoh, only kneeled before him, never prostrating themselves fully, as they would before the Pharaoh. But when the children of Israel–foreigners arriving in the land many years after Yosef’s appointment–saw how Yosef ran the ‘show’, they made no distinction between the status of Yosef and the Pharaoh, and therefore prostrated themselves fully.
A Kabbilistic view on the issue is as follows: The sovereignty of Yosef-a lofty G-dly soul from the world of Atzilus (don’t bother googling)-was a physical representation of the sovereignty of G-d. And kneeling and prostrating, were, respectively, a less and more extreme physical expression of the state of subjugation Yosef’s G-dly reign effectuated in his subjects .
The Egyptians, inhabitants of the land that was at least then known as the “Nakedness of the Earth”, were not brought to the utter subjugation embodied in the act of prostration; They were only brought to their knees. The children of Israel, on the other hand, were brought to an Abrahimic “I am but dust and ash” nullification before G-d, by virtue of their superior spiritual level; they prostrated “faces to the ground”.
We await the complete manifestation of G-d’s Kingship, in the Davidic Kingship of the Moshiach (Messiah). When all the nations will serve G-d, side by side.