Xury and Friday are very similar in that they act as faithful, reliable, and very helpful servants or slaves to Robinson Crusoe. Both look to Crusoe for guidance as their superior, and both follow his commands. Both accept that Crusoe deserves the fruit of their labors.
Crusoe "inherits" Xury when Crusoe runs off with one of his Moorish masters' ships to gain freedom. Crusoe shows Xury similar respect to the respect he shows Friday, which is to treat both as children in need of his guidance, but a difference is that Xury is a child. Crusoe respects him more because he comes from what Crusoe regards as a civilized culture. Crusoe does not rename him and does not try to convert him to Christianity, whereas he does both with Friday. Friday feels a deeper bond to Crusoe than Xury did because Friday credits Crusoe with saving his life. Friday voluntarily binds himself to Crusoe.
Crusoe has some qualms about selling Xury into slavery and settles, with Xury's agreement, on putting him into ten years of bondage instead. As with Friday, Crusoe perceives Xury as a possession that he can dispose of. As with Friday, too, Crusoe values Xury for what services Xury can provide for him. Nevertheless, Crusoe's bond with Friday is closer and deeper than the one he has for a brief time with Xury.