The big difference is the modular designs and the difference that you look for is what type of motors are used, 3-phase, if so they have three wires and an ESC. The parts on Hobby grade are interchangeable between about all other hobby grade quads, though they might be the wrong size (15 amp ESC vs 40 amp ESC).
Toy grade quads often use coreless DC motors, need no ESCs and only have one PCB.