The only difference is that BTC is regarded much safer and faster than PayPal.
Paypal payment is almost instant. Bitcoin transaction takes several hours, depending on the fee you pay and how many transactions are ahead of yours.
Bitcoin doesn't take several hours. Mostly you get at least 1 confirmation within 30 minutes. I have once seen my deposit on an exchange that requires 3 confirmations to post within 10 minutes. It's all relative.