eBay Inc. owns PayPal, but in some ways, they remain independent.
Sign up for an eBay account and PayPal account.
Become PayPal Verified.
Link your eBay and PayPal accounts.
If you want to buy on eBay using PayPal, you should consider confirming your address with PayPal.
If you want to sell on eBay and accept PayPal payments, you'll also need to accept PayPal on your eBay listings.