What is the difference between this and the Programmable Banking project OfferZen was previously involved with through Root?

This is semi-complicated to answer, you can read the back story here.

TL;DR: Root pivoted to insurance, Investec was inspired by their Programmable Banking offering and decided to roll their own. Root is not involved anymore on the product but are excited to see Investec join the pursuit of opening fintech infrastructure to devs.