Well, I just made up those names as placeholders; there's not much you can do outside varying the resource cost, tonnage, research cost, supply usage, and speed of the various engines. You can't, for example, make some engines only work for traversing warp points. I just wanted names that sounded different enough that you wouldn't wonder "why can I install an ion engine and an antimatter engine on a ship but not two ion engines? they both function basically the same way"
Also to create more interesting tech names than "Ion Propulsion", "Antimatter Propulsion", "Photon Propulsion", and "Quantum Propulsion"