Websites can use the Paypal or any other widget that captures payment information. Enfold recommends that the payment processing entity is compliant with PCI Security Standards Council's specific Data Security Standards. Amazon Payments, PayPal, Google Wallet, Stripe are all compliant.
Ploud was not built to store or process payment information, nor is compliant. Ploud forms should not be used to capture or store credit card data (or any sensitive information, e.g., Social Security Number) directly on a website's file systems.