In terms of market price I doubt. Indeed there are differences with the rate of increase on these two but I think parallelism is still evident with Bitcoin and Ethereum market price if we would check a wider timeframe. They're just two different chains and tokend as well, so we cannot expect for a totally same price action. In terms of stability, not sure but I observed a better market price stability with Ethereum especially on the recent market crash so I guess it is still as promising as ever. If this is to the idea of whoch coin to invest then I'd suggest choosing both or diversifying your wallet to these two to have better investment performances than just choosing a single coin.
No I don’t think Ethereum will ever catch up with Bitcoin if what you mean is be a higher $ price or surpass adoption. Bitcoin is the King of crypto & always will be, it’s better in every way. It has a much lower supply with a fixed cap of 21 million, compared to Ethereum where the supply is almost endless. Bitcoin is proof of work compared with proof of stake with Eth. Transaction/Gas are much higher with Ethereum. I don’t see Eth catching up with Bitcoin in any way.
It wouldn't likely to catch up. Bitcoin has a bigger community to start things with. There are numerous of pumps we saw before and it's been proven that ETH will just remain next to Bitcoin, in all aspects.