BTC addresses use Base58 (like Base64 but with no very similar character: IOl0+/) and must begin with both one, three, bc1q or bc1p based on which kind of address it can be. Your Ethereum address is your identity within the Ethereum network. It is needed to communicate with the network https://ethereum-vanity-address-g13185.thekatyblog.com/28536085/vanityeth-an-overview