Orange: Soverign Grace.
Trent: Semi-Pelagian
Trent is not semi-Pelagianism. It does not say the human will cooperates in it’s own salvation, but prepares the path. The salvation is still totally up to God. The person can cooperate to prepare the path, and still not end up being saved. It is logically necessary, since salvation could be refused, which we know to be true. If salvation were irresitable, then we are only meat puppets - machines. If so, then salvation has lost its value. Salvation only has value if the one saved has a free will to reject it.
Semipelagianism taught that man can make the first move toward God without grace, and then grace takes over the rest. Augustine and Orange teach that no, even the *initial* conversion must be preceded by grace. Trent taught exactly the same thing:
The Synod furthermore declares, that in adults, the beginning of the said Justification is to be derived from the prevenient grace of God