Mudiay plays and thinks more like a PG and Russell is actually a SG who can pass at a high level but he's much more of a scorer. I think Russell's game fits the Knicks best. The reason is that Combo guards do better in the Triangle than ball dominant PG's.
This offense doesn't really utilize the PG skills, whereas a Combo guard who is mostly looking to score is much more comfortable in this system. Russell can catch and shoot but also work the 2 man game and drive. The Triangle doesn't really have many plays and isn't really a PG dominant type of offense.