BTC has already established a legacy and is the most famous crypto of all time. While ETH is like the modern pop songs right now, popular to new members and a lot of rising industries, slowly considering the idea of using more than any other coin. They are different for me when I look up on the function in the current market.
ETH could never be like BTC unless it will also receive the attention and fame of BTC during its golden era. BTC is more used for gambling and investing right now while I see ETH more as a real monetary system for transactions.