I've been down this road quite a bit on Amazon, eBay, and AliExpress/Alibaba. Are there any good options for relays that work for 100-200amps? I've found 30 amp relays of the type that are built into PCBs and I have tried a few 100 amp contractors that can be triggered with a separate line but I'm not sure I trust them. Most tend to top out at 65a rating and I get the feeling the 100a ones are just the same but with a more belligerent seller willing to advertise a false rating. What serious options are available for switching larger loads remotely.
Relays and contactors are the same thing. The main difference is that they tend to be called contactors more often when they are carrying mains voltage and current. (Or higher.)
It's very common to use a relay to control a contactor.