According to the concept of the seven "shepherds" (the Biblical figures corresponding to the seven lower Sefirot), people are constructed along certain lines, not necessarily biological, which are soul paths.
Every person is thus bound up with these lines connecting him with the seven shepherds.
The difference between souls is a matter of proportion.
That is, not only is it a matter of levels of being, it is also a question of degree or emphasis on one attribute or another.
It may be compared to the common tendency to trace characteristics along lines of visible, genetically inherited qualities.
This child's hair is like his mother's, another resembles his grandfather, and so on.
Every child of Israel thus has something of Moses in him and something of Aaron.
The spark of Moses enables one to have the Shekhinah speak in his throat, extinguishing oneself in the process.
The aspect of Aaron provides one with the capacity for the Great love.
From which it follows that a person can perform in two ways:
He has the potential to nullify himself completely, and he also has the driving power to go ahead and do whatever has to be done.
The "doing," whether as Divine worship or routine functioning, is in its totality a ritual
of love.
All doing is an act of giving, a work of offering.
–Rabbi Adin Steinsaltz
From "Sanctity and Restraint" in The Candle of God by Rabbi Adin Steinsaltz