int vs troll
The method. "int" is losing on purpose by dying; "troll" is sabotaging the game by any means. Inting is one kind of trolling among others.
int
"int" is short for intentionally feeding: dying on purpose to hand the enemy gold. It is precise, it is observable, and it is punished. A player who runs into the tower five times in a row is inting. A player who loses their lane is just losing their lane.
open the page →troll
"troll" covers everything that ruins the game for your own team: the absurd pick in champ select, refusing to play your role, farming the allied jungle, stealing kills on purpose, inting too. Broader, so vaguer, and more often used wrongly.
open the page →Why they get mixed up
Both are accusations, and both get thrown too fast. The useful difference: "int" describes a precise behaviour you can report, "troll" describes an intent you are guessing at. An unusual pick is not trolling, a bad game is not inting. When in doubt, saying neither is the best option.