Great question. The differences are actually pretty big, but might not be completely evident at a glance. Let's break it down:
At a high level, Leash and Cuff are minimalist straps. They maximize function and minimize size. Slide and Clutch are built for comfort and to fully meet the needs of professional photographers.
Breaking it down further:
Leash is ultra-minimalist and versatile. It can be used as a sling strap, neck strap, safety tether or video stabilizer. Leash can easily removed and compacted down to store in your pocket. It's made of unpadded 3/4" wide seatbelt-style webbing.
Cuff is a simple quick-connecting wrist strap. The purpose of Cuff is to provide security against camera drops in as small a package as possible. Cuff is made from unpadded 3/4" wide seatbelt-style webbing and can store on your wrist as a bracelet when not in use.
Slide is a quick-connecting, comfortable, padded professional-grade camera strap designed for carrying heavy cameras for a long time. Slide is wearable as a sling strap, shoulder strap or neck strap. Slide is made from 2" tubular seatbelt-style webbing with padding hidden on the inside. One side of Slide is smooth, the other grippy.
Clutch is the only quick-connecting, quick-cinching camera hand strap ever made. Unlike Cuff, Clutch helps you actively grip your camera. Cuff is made from durable Hypalon, EVA foam padding and a microfiber inner.