What's the difference between a tool chest, a rolling cabinet, and a modular stacking system?

A tool chest is typically a drawer unit (portable or topper), a rolling cabinet sits on casters as the base, and a modular stacking system uses interlocking boxes that clip together. Many of the picks here are 'combos' or detachable 2-in-1/3-in-1 units that blur those lines, so match the format to whether you mostly need portability (stacking/portable) or fixed shop storage (rolling cabinet).