Xapo and coinbase both don't have private keys unlike blockchain wallet. However, the difference between the former wallets is that your account is secure and there are ways to recover your coins if you lose your password which is not possible with blockchain.
Because AFAIK, XAPO and coinbase both were using the shared wallet (I came to know by checking my xapo
BTC address into blockchain and i found some transactions that i never done also faced the same thing on my coinbase wallet too).