ETH 1k and Bitcoin 4k would have ETH at a higher market cap than Bitcoin (not that market cap matters, but it's the only measure I can think of).
Market cap does matter, the problem is - people often misuse it with nonsense like "Bitcoin lost 5 billions USD of its value over a few hours" to sound more dramatic, while the real purpose of market cap it so compare value of assets against each other. Different assets have different supply, so by multiplying the price of a single unit by current supply you can get an idea of how expensive the asset is.
ETH 1k vs BTC 4k would mean that for some reason there's more money invested in ETH than in BTC.