What are the fundamental differences between the two? I come from an Ethereum background and am fairly new to Hyperledger Fabric. I've heard people talk about "channels" in the Fabric ecosystem and it sounds quite similar to the concept of sidechains. It'd be awesome if someone could clarify the differences between the 2 (if they exist).
Since Etherium is a token-based blockchain, my understanding of sidechains is that they allow tokens to be transferred between the main ledger and a "child" ledger (the sidechain). Since Hyperledger has neither a native token nor the concept of "child" ledgers, I don't think they are really analogous to channels.
Hyperledger channels allow for private communication between a subset of peers on the network. Only those peers on the channel receive transaction data for the channel. Even if separate channels are not required, a single channel must still be defined, then all peers communicate on this channel. In this way, there is no main ledger in Hyperledger, as each channel effectively acts as a separate ledger.