It goes without saying that a name like Samsung Pay Mini would mean it is a far more lightweight version of its current Samsung Pay service, which has seen action only for online payments and does not allow contactless payments via the MST standard (Magnetic Secure Transaction). Just to make sure that we are all on the same page, MST happens to be one of the main selling points of Samsung Pay, since Apple Pay as well as Android Pay does not support such a standard.
With the Samsung Pay Mini app, one can have a simple and pain-free method of storing credit/debit card data on a device, enabling a quick and convenient method of purchasing just what you would like. It can also stash incoming receipts, and security is touted to be delivered by a 6-character passcode and/or a fingerprint locking.