From some API spec I have:
Force to place an Auth transaction into the current batch (PostAuth) or to place a transaction not processed through the LUCY Gateway™ into the current batch (ForceAuth)
So "AUTH" just places the funds on hold. If you want to have the funds transferred to your merchant bank you'd need to do "SALE" or "CAPTURE" or something. But what's the point of "FORCE"? Does "AUTH" not put the funds on hold immediately? Do you need to do "FORCE" to do that?
FORCE is also known as CAPTURE ONLY. This transaction type allows you to manually capture funds for transactions that were previously authorized outside the payment gateway. Additionally, because a Capture Only requires the Authorization Code of an original, successfully authorized transaction, you can use this transaction type to force captures for transactions that were declined by the payment gateway as a result of Address Verification Service (AVS) or Card Code Verification (CCV) rejection settings. Though they were declined by the payment gateway, an Authorization Code is usually still issued by the credit card issuing bank.
Force (Capture)
A Force transaction takes an existing authorization number obtained from an Auth Only transaction and forces the sale through so the merchant may receive those funds. Unused funds from an authorization are immediately freed for the customer to use.
Force is a special transaction in credit card processing.You will use the force credit card transaction when you can't get authorization the normal way. This can be, for example, when the credit card charge amount is large and the credit card company wants to talk to the merchant over the phone before authorizing the transaction. There are other reasons as well. Over the phone, if it is approved, the credit card company will give an approval number. Now you need to charge the credit card transaction as a "Force" transaction in order to get through.
