> If you don't have a preferred block source (trusted peer), Bcoin will be started automatically and synchronized with the mainnet chain.
(From https://github.com/bitpay/bitcore-node/blob/master/README.md)
i am not really familiar with bitcore myself so if i am wrong hopefully someone will correct me, but i believe that you can do both. meaning a standalone Bitcore as your full node or just add it on top of another full node (bitcoin core) and use it. what Bitcore does is basically indexing the blockchain so it becomes easier/faster to find things like a block explorer finding any address balance. which is why it takes a bigger size.
https://bitcore.io/guides/full-node/