eSCO is the SCO that’s being replaced right now. It’s a combination of the backend of New POS, with the guest-facing UI of tSCO, and some other Classic POS pieces of software in there too, hence the 4 digit pins and super slow restarts.
tSCO is the old old SCO software, introduced in 2016 to replace the default NCR SCO software that every other store uses. Majority of stores updated to eSCO in January 2020, but a few still used tSCO until a few weeks ago, when they updated to New POS. It’s basically Classic POS on the backend, store mode, etc… but with a different UI for the Guest Facing portion.
In short
tSCO (Target Self-Checkout): Runs on Classic POS 100%. Decommissioned January 2021.
eSCO (Enterprise Self-Checkout): Fusion of Classic and New POS internally in the software. Guest Facing portion is the same as tSCO, but Store Mode is redesigned. Made as a stopgap between tSCO and New POS in ealry 2020 when corporate thought New POS would be 100% chainwide before the end of 2020. (COVID threw a wrench in that.)
GUX (Guest User Experience): The name of the SCO app on New POS. Completely redesigned, same software as all the other registers in the store.
(All the New POS apps have names. FLUX [Front Lanes User Experience] is the checkout app, SBUX [Starbucks User Experience] is Starbucks, AUX [Advocate User Experience] is Guest Service, etc…)