Just like Artell and Sergio, one was an assassin in Eastern Europe during the Crusades and the other was an assassin in Italy during the Cultural Renaissance. Their clothes are different in color. Artell is white, while the latter is silvery white.
Before Joe, there was no branch of Italian assassins, and Joe was founded in the Brotherhood. Therefore, in the previous clothing, that is, the assassin's clothing left by his father, it should be designed because of his blood relationship with Artell.
And because the headquarters created by Atle is the initiator of other divisions, most other divisions are designed in white, or white is the main color, which can be seen in every generation of games.
But in any case, the white color, which is completely opposite to the black of the familiar assassin suit, highlights the unique strength of this series. White is conspicuous day and night, so the assassins in Assassin's Creed are very skilled.