Only appreciable difference(s) between attachments made for skidsteers and tractors using the SSQA is the ones for skidsteers tend to be heavier than those built primarily for compact/sub-compact tractors, and the hydraulic flow requirements for attachments with hydraulic motors (e.g. hydraulically-driven mowers and augers).
Otherwise there is no difference as the physical interfaces for the SSQA plate is the same, and they can be used interchangeably. Now the hydraulic couplings may also be different as most implements for skidsteers will likely have flat-face couplers, and those for tractors may have pioneer/ag-style couplers, but it's easy enough to either change the hydraulic couplings - or just assemble an adapter from a pair of each of the respective couplers. For example, a few years ago I bought a Danuser Intimadator which came with flat -flat face hydraulic couplers while my tractor has the ag-style hydraulic couplers; rather than change the couplers on the Intimadator I bought a set of flat face couplers, a pair of 90ー elbows and a pair of ag-style couplers and assembled them into adapters. This has allowed me to leave the original flat face couplers on the Intimador (or any other implement with flat-faced couplers) while also leaving the ag-style connectors on the 3rd function hydraulic couplings on the tractor.
The SSQA interface is the SSQA interface which has been standardized for all machines that use it .... which includes almost all modern compact tractors (John Deere being something of an exception as it's an option vs. their own interface), many modern sub-compact tractors, all modern skid steers (at least in the US), along with some models of: compact telehandlers, compact wheel loaders, TLBs/backhoes, and likely other machines.
Hopefully this clarifies more than it adds to the confusion. :thumbsup: