-PayPal Standard (IPN): takes the customer to PayPal's site AFTER the ENTIRE checkout in order to make payment. The customer can pay without having a PayPal account (depending on what country you are in as PayPal limits that feature for some countries). After the payment is completed, your store is notified (via IPN) of the completed payment, after which time the order is stored in your database. PayPal sees Website Payments Standard as a solution for merchants wanting to collect payments on their site easily, especially if they have no other payment method available.
-PayPal Express Checkout: gives the customer two options: They can jump over to the PayPal site to login to their account BEFORE completing checkout on your store (which allows them to select their address information there and never have to re-type their address details on YOUR site, thus the "express" part of the transaction) and then choosing shipping choices and discounts/coupons etc before completing the order OR they can go to the PayPal site to login to their account AFTER making shipping/payment/coupon selections on your site (and creating an account on your store and typing their address info on your store), much like they do with Standard. The second option is where the "PayPal Express Checkout" plugin comes into play. You can actually enable or disable this.
-PayPal Payflow Link: is essentially *only* a merchant account. Transactions conducted via Payflow Pro (for US Merchants) do not appear in your PayPal account. Instead, they are forwarded directly to your merchant bank account. Basically, Payflow is just like any other traditional payment gateway (Authorize.net etc). In North America you can connect the Payflow Pro service to your own merchant bank account. In the UK, the Payflow Pro service is actually bundled as a hybrid service with Website Payments Pro, connecting all the transactions to your UK PayPal account, and all monies are deposited to your PayPal account, instead of directly to your bank account.
-PayPal Payflow Pro: See above "PayPal Payflow Link"
-PayPal Web Payments Pro: appears to the customer only as a couple fields to enter their credit card number directly on your website. They have no idea that in the background you're processing their card via PayPal. They have to make an account on your site, and supply the address details, but once they confirm the order, the payment is collected immediately and the order saved. It doesn't rely on IPN to release the order. However, it does store any transaction updates done on the PayPal end such as refunds etc as long as IPNs can be received by your server. Website Payments Pro is currently only offered in the USA, UK, and Canada. A monthly service charge applies, and there is an account application process and credit check to complete before the feature can be activated on your account. PayPal Express Checkout must be enabled in order for Website Payments Pro to be offered on your site. PayPal sees Website Payments Pro as a payment gateway for handling credit cards. That's exactly what it is. Coupled with Express Checkout, it gives your customers the maximum amount of choice about how to pay: either by credit card directly on your site, or by using their PayPal account to submit payment.
Most of the modules include instructions on setting them up directly on the module settings screens. Additional detail is provided below.
-PayPal Standard (IPN): Simply install the "PayPal Standard" payment method module and then click on the wrench icon to edit the settings once installed. Add your PayPal email address and save the settings. Ready to start taking PayPal.
-PayPal Express Checkout: Simply install the "PayPal Web Payments Pro" payment processors module and it will install the "PayPal Express Checkout" payment method module and the "PayPal Express Checkout" plugin automatically. Once installed, alter the PayPal Web Payments Pro settings by clicking on the wrench icon. Add all of the API credentials as prompted. Save the settings. Keep in mind that unless you are planning on using "PayPal Web Payments Pro" payment processor module, you do not need to enable it. The API credentials will be used for Paypal Express only.
-PayPal Payflow Link:
1.) Change the value of the "User ID" to your assigned login id from PayPal.
2.) Change the value of the "Partner ID" to your assigned partner id from PayPal.
3.) Save the changes by clicking the "Edit Module Settings" button and then activate the module.
3.) Log in to PayPal Manager.
4.) Click "Service Settings" on the menu bar and then click on "Configuration" for Payflow Link.
5.) Click "Payflow Link Info" on the Account Information sidebar.
6.) Under the heading "Form Configuration", locate the first field called "Return URL Method". Change the value of this to POST.
7.) Under the same heading, locate the second field called "Return URL", check the box and change it to "http://www.yourdomain.com/sunshop/checkout.php?return=credit_card". You can also make this a secure transfer using https:// if you have a SSL certificate.
8.) Under the same heading, locate the second field called "Silent Post URL" and change it to "http://www.yourdomain.com/sunshop/checkout.php?return=credit_card". You can also make this a secure transfer using https:// if you have a SSL certificate.
9.) Under the heading "Receipt Display Options" be sure to change the value of "Receipt Button Text" to the value of "Complete Transaction". This insures that the buyer returns to your cart to update the database and get their receipt. If they do not click this you will still be ok as long as the "Silent Post URL" is set correctly.
10.) You are done but you can make any additional changes you wish on this form. Be aware that you can change the colors of the checkout process here as well as a few other useful items.
-PayPal Payflow Pro:
1.) Change the value of "Merchant ID", "Login" and "Password" to your assigned information.
2.) Note that your Login can be set the same as your merchant id if you did not setup a separate user account.
3.) Change the value of "Partner" if necessary.
4.) Change the value of "Test Mode" from "On" to "Off" if you want to put the shop in LIVE mode.
5.) Save the changes by clicking the "Edit Module Settings" button and then activate the module.