Leather tends to be softer, plastic support structures stiffer, and insulation often varies. Lace covers and gaiters help keep water out, while higher cuffs provide more support.
Traditional lacing offers fine adjustability from ankle to toe, while a ratcheting system makes it quick and easier to dial in a close fit. Boots with lace overlays use an additional zipper closure to keep the laces protected.
Your boot and binding types must use the same system. NNN BC boots work with NNN BC bindings. SNS XA boots require SNS XA bindings and are not compatible with NNN. Three-pin duckbill boots work with three-pin Nordic/backcountry bindings or tele bindings.