That is why I put "Calvinist" in quotes. In reality, it is more proper to say that both Augustine and Calvin were Paulists when it came to the doctrines of grace. There were differences, but Augustine's theology developed into something which was more like the Reformed theologians of later years than like the Arminian or Pelagian theologians.
The major ,and I mean major difference is that Augustine(along with all the other fathers) understood the Sacraments (especially the Eucharist)as Channels of Grace.
Calvinist Ignore the fathers regarding this and side with John Calvin. Therefore John Calvin is their pillar and foundation of truth.