There are two main differences between OSAS Arminian and Calvinism:
1) In OSAS Arminian, God picks the world in the world ensemble to actualize when comparing all possible worlds so that He saves the most and damns the least. Whereas in Calvinism, its god does not have this conscientiousness, conscience and consideration for he evil and unable. In any case, he is lesser than God.
2) In the world that we do exist, all that has happened and will happen is predetermined because it is the world God selects and actualizes for eternity since it is the best one. The reason why Calvinism even if it accepts these terms still would be evil and a sign of unsalvation is because it teaches a wrong attitude in the unregenerated spirit of the Calvinist. Their god does not provide sufficient grace for all or any to have the choice by irresistibly imposing salvation on the allegedly saved. The contradictory two wills of the god of Calvinism telling everyone he wants them to be saved while secretly not is doubleminded. And the god of Calvinism pleads (or not in the case of hardened Calvinists) for our salvation is duplicitous by giving false hope to the reprobate.
Thinking in these terms gives me peace in reconciling to a certain degree God's infinite foreknowledge and determinism with free will. May the Holy Spirit touch your spirit with this truth. Even in this actualized world William Lane Craig is not saved, because he refuses to come to Christ by saving faith instead of by works, for he admits his faith is one where he can lose salvation by works. There is no world in which he would be saved, for it would be unrighteous of God to send someone to Hell in this actual timeline if they could have been saved in another. Therefore, William Lane Craig truly belongs in Hell.
Anyone who is saved in this world may have been unsaved in another world, but anyone who refuses salvation in this world could not have been saved in another world, for they either would not have existed or would receive Christ. A computer programmer would set it up just this way. How much more for God!
This is the best explanation I have ever heard, so I am abiding in my own conscience with it.