While I do claim (and insist) that our faith subsequent to salvation is indeed of the same source as our salvific faith—the Spirit of God is that source—I think there is still a stark difference, in that while our faith is a RESULT of the Spirit taking up residence within us, we have no force of will nor agreement causal to our salvation that IS through that faith. We find that we do believe, and that the subsequent act of will of submitting our will to the one in whom we believe is indeed a work, even that is only a result, still, of that faith and the specific (not simply a general 'enabling') work of the Spirit in us. The difference could be seen as the fellowship causally resulting from the willed 'opening the door' (a la Rev 3:20) and obedience (John 14:23) vs the regeneration that may not even be understood or conscious to the new believer.
What I think has not often been well-defined in this discussion, and in most theological circles, too, including Bible and Theological Dictionaries, is that Monergism, while usually well-enough defined, Synergism comes with the definition of synergism as mere 'cooperation' of the sinner with the Spirit of God in bringing about salvation, which definition is lacking one strong fault of true synergism, that God's work alone is not enough, but that the sinner must be willing, and in most circles, even accepting or enabling in some way for God to be able to do his work of salvation—not just cooperating, but ADDING to God's work. This is at the crux of Irresistible Grace—I call
@Eternally-Grateful a synergist, yet he finds the difference in terminology miniscule between us. Well, the meaning behind the terminology is anything BUT miniscule.
I will happily grant that he is not your usual synergist, but in the end, he thinks salvation must be a result of one's accepting of the Gift of God, and, I'm sorry, but that is synergism, since the salvation must come through the willed act of accepting it.