Can you tell me what these do and what the differences are?
These are essentially adapters that allow Ethernet-like connection, but rather than using actual Ethernet cabling, they use the existing wiring (electrical/coaxial). Depending on how your home is wired, either one could be a reasonable solution; providing faster than WiFi (but slower than true Ethernet) speeds.
MoCA uses your existing cable TV (coaxial) cables to run the network connections. Powerline uses your existing electrical wiring. Connect one adapter close to where your router is located and the other near where your computer is located. Depending on where your splitters are located, your performance will vary.
Which would be easiest from just router to pc, I don’t want to change the whole network or internet plan
Set up should be about the same for either scenario. If I were to pick between the two, I'd probably opt for a MoCA set up as there are likely fewer junctions between where the router is and where the PC is. In either case, it would be wise to use a store that has an excellent return policy just in case your selected option doesn't work out for you.
-Wolf sends