create new channel and join peers - hyperledger-fabric

Question

I have few basic doubts regarding creating a channel in fabric. I was trying to set up the first network with individual commands.
I came across multiple commands for creating channel but unable to understand the difference
a. sudo docker exec peer0.org1.example.com peer channel create -o orderer.example.com:7050 -c composerchannel -f /etc/configtx/composer-channel.tx — tls true — cafile /etc/configtx/crypto-config/ordererOrganizations/example.com/orderers/orderer.example.com/msp/tlscacerts/tlsca.example.com-cert.pem
b. peer channel create -o orderer.example.com:7050 -c mychannel1 -f ./channel-artifacts/channel1.tx --tls $CORE_PEER_TLS_ENABLED --cafile $ORDERER_CA
Does channel need to be created under an orderer container or peer container?
in the above command I can see peer0.org1.example.com with exec, is it given to create the channel inside the peer container?
In the command b peer0.org1.example.com is not given, is it because we run this command inside CLI?
I just wanted to understand how to works with the channel creation syntax?

Answer 1

I can see why this can be confusing. At a high level:
In order to create a channel, you need to submit a configuration
transaction to an orderer node (aka "create channel").
In order for peers to receive blocks from a channel and to invoke
chaincode on a channel, you need to call the "join channel API" on
each peer.
The confusing part is that there is only a single CLI (command-line interface) for performing both actions and it is actually the peer executable.
So when you call peer channel create ... you are actually sending a configuration transaction to an ordering node.
You can either execute the peer ... commands inside a container which has the peer executable ( that's the docker exec ... you show above ) or you can run the peer binary on a host system and do the same thing (the second option you show above runs it within the CLI container).