Newer styles are all types of materials from lightweight nylon, to Gore-Tex, to Neoprene, to Hypalon, Supplex, etc. Soles are either plain felt or felt with cleats or studs imbedded in the felts. More comfortable to wear for long periods. Separate boot fits foot better and gives more support. Just another kind of wading boot, but they are designed to be worn without waders.
Uppers are usually neoprene, with a heavy side zipper.
Stay away from Velcro Strapped Boots - They can be unstrapped by heavy current and pulled right off your feet. Wading Jacket or Cheap Poncho Handy if you fish in bad weather a lot.