Irresistible grace: the notion that when God extends grace to a person, they cannot reject it. Like unconditional election, the person has no choice over the matter.
Resistible grace: John Wesley in 18th-century language taught that God extends prevenient (preceding in time) grace to all. But while Calvinists hold that grace cannot be resisted, Wesleyan Arminians believe that it enables, but does not ensure, personal acceptance of the gift of salvation.
Contrary to what some Calvinists claim, Arminianism is not the equivalent of Pelagianism or salvation by good works. Prevenient grace precedes human decision, existing prior to and without reference to anything humans may have done. God takes initiative in the salvation process and his grace is available to all people.