Those are the strongest competitors in the field, but they are still very different when you look at their architectures. One is valuing efficiency of decentralization (BSC) and for ETH it is the other way around. As of now you can't have both on a high level. It is a trade off that is so hard to solve although BSC doesn't pay as much attention to decentralization anyway.
Yes, they do compete fairly in the crypto space, but BSC is only seen by some because of its cheap transaction fees, whereas ETH is seen and chosen by some because of its price recovery which tends to be quick when market conditions normalize.