Is there a comparison chart where one compares Rootstock to Ethereum? What are the pros/cons of each system?
Rootstock's smart contract features are identical to Ethereum's, both use the EVM. Contracts on Ethereum are deployable on Rootstock, and vice versa.
They start to differ when you look at the networks. Ethereum has a main network where all the contracts run in a decentralized manner. Rootstock is a sidechain of Bitcoin, but it is not a two way peg, instead it is a federated peg with some amount of merge mining.
A federated peg means that to convert your RSK back into Bitcoin, there are federated parties, or "gate keepers," that control the conversion back to Bitcoin. These gate keepers mean the whole system is somewhat centralized. In the past I'd even heard there would be additional fees for entering back into the parent chain, I don't know if that panned out, but it is certainly possible.
It sounds like an alternative unfederated version is possible with merge mining, and it is being worked on. One thing to note with merge mining and sidechains is that even though chains are rooted in the parent chain, they are mined/managed differently and so have different security properties; most likely the parent chain will be more secure than the side/merged-chains.