A wrap-around canvas and a cradled canvas are not the same thing. 

Every canvas that is mounted on a stretcher is a wrap-around canvas. It may or may not be framed after painting. If framed, the fabric round the stretcher serves as the allowance for the framer to lay the canvas neatly under the frame. If unframed, painters usually extend their work to include and cover that allowance.

A cradled canvas is box-like and has sharp edges. It is meant to be unframed, has wooden panel backing and adequate bracing. The cradle sides are usually painted black (or any color, actually) and serve as the actual, albeit non-visible, frame for the painting.

Wrap-around canvases can be un-tacked and rolled for transport.

Cradled canvases cannot be un-tacked. The entire canvas is mounted flat on a wooden panel. If one attempts to do so, the entire canvas will disassemble and its purpose will be ruined.