What's the difference between a wrap, a sling, and a soft-structured carrier?

A wrap is a long piece of stretchy fabric you tie around your torso (Boba, Solly, KeaBabies). A pre-wrapped sling like the Baby K'tan slips on like a t-shirt with no tying. Soft-structured carriers (SSCs) like the Grownsy use buckles and padded straps and generally work better for older, heavier babies and longer wears.