I need to implement PayPal on my web page, and I don't know which one to use, Paypal Payments Standard or Paypal Express Checkout or both. To me they seems pretty much the same.
PayPal Payments Standard allows users to pay by card even if they don't have a PayPal account. PayPal Express Checkout requires that users have a PayPal account or create one in order to check out. Both services are detailed on PayPal's merchant page.
You should use PayPal Express Checkout if:
You should use PayPal Payments Standard if:
You can, of course, include both if you wish, and label the Payments Standard checkout method as 'pay with card' and the Express checkout method as 'pay with PayPal'.