I believe that Ethereum really has a huge potential for successful and consistent development in the future, provides opportunities for the work and development of many new altcoins and ICO. But in any case, Bitcoin will continue to be the king of the crypto market.
The other point of difference in both of them is that Bitcoin is a currency which is very hard to replace by any other coin or we can say it is unable to replace while ethereum can easily be replaced by any other coins. So Bitcoin is the best even in this regard.