btcd, and presumably other bitcoin node implementations, seem to have 4 network options:
I get that mainnet and testnet both are "public" in that your node will communicate with other nodes and that both have an existing blockchain and genesis block.
However, from what I can tell, both simenet and regtest both create a local only blockchain, and both will create a new genesis block. I this case, what is the difference, and which is better (easier) for developing bitcoin applications?
This is what the documentation has to say:
--regtest Use the regression test network --simnet Use the simulation test network