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.
I have had a PayPal payment reversed after 3 weeks when I sold a CPU to a scumbag on eBay who said that it wasn't working. PayPal transactions take 180 days to confirm before the money is truly yours.