So, what’s the difference?
“The difference between them is not primarily one of emphasis, but of content. One proclaims a God who saves; the other speaks of a God who enables man to save himself. One view presents the three great acts of the Holy Trinity for the recovering of lost mankind–election by the Father, redemption by the Son, calling by the Spirit–as directed towards the same persons, and as securing their salvation infallibly. The other view gives each act a different reference (the objects of redemption being all mankind, of calling, those who hear the gospel, and of election, those hearers who respond), and denies that any man’s salvation is secured by any of them. The two theologies thus conceive the plan of salvation in quite different terms. One makes salvation depend on the work of God, the other on the work of man…” J.I. Packer “Introductory Essay,” in John Owen, The Death of Death in the Death of Christ: A Treatise in Which the Whole Controversy About Universal Redemption is Fully Discussed, page 4.
Also check out, What is Reformed Theology by R.C. Sproul.