I'm not sure what is the difference between regtest and testnet, they seem are different things but i cant find the different between them.
Does one have more stuff than others?
On the regtest, peer are seem to not being found.
Regtest is a network designed solely to be private and for testing only. You can create a private regtest network and do testing and experimentation with it. It is not a public network and has no peers for you to connect to.