What PayPal is doing in so far as bitcoin is concerned is baffling to me thus far. Unless they have plans to allow buyers to withdraw their coins or let them use the coins for purchases at places that accept crypto, I'm not sure why they even dipped their toes into the crypto waters to begin with.
You can buy/sell Cryptos in Paypal like other exchanges. Sometimes it is easier to buy/sell crypto on PayPal than a regular exchange, regular exchanges like Bittrex, Binance are so much complicated for newbies. People who are not experts & knowledgeable enough to keep their private keys or wallet data secured can easily use PayPal cause it is reputed & US govt. regulated platform. Everyone is free to buy/hold cryptos in USA via PayPal and is able to take the profit by selling them.
No regular exchange gives you private keys as PayPal does. so, the only difference is you can't make a withdrawal request to move your cryptos from PayPal directly to your other wallets. You have to sell your holdings and then you can transfer the electronic fiat from PayPal to your Bank Account or MasterCard.
So there is no big difference in PayPal from other regular exchanges, Both of them are denied to give you private keys of your wallet.