Jansenius: Adam's help 'without which', Christ's help 'by which'
Thesis VI. Jansenius, bishop of Ypres, presses this distinction again and again as of the greatest weight in the book he titled Augustinus, where he collects and explains the difference between the two graces at length from Augustine.
He puts the difference here. The grace given to man before the fall was a help without which the first man could not will good, but it did not make him actually will it.
The grace Christ gives fallen man makes him actually will. It is not merely a help without which, but a help by which the willing of good is itself produced in him.
Latin
VI. Hanc distinctionem, ut maximi momenti, saepius inculcat & urget Jansenius Episcopus Iprensis libro cui fecit titulum Augustinus. Ubi gratiae istius utriusque discrimen, prolixe ex Augustino colligit & explicat. Illud autem discrimen in eo constituit, quod gratia data homini ante lapsum adjutorium erat, sine quo primus homo non poterat velle bonum; sed quod non praestabat ut bonum actu vellet. Gratia vero quam Christus homini lapso largitur, efficit ut homo actu velit, & est auxilium, non simpliciter sine quo, sed quo ipsum velle bonum in homine producitur.