Whats the difference between a Pokemon Trainer and a Pokemon Hunter?

From the (admittedly very few) examples seen in the anime, hunters use traps, poisons/sedatives and various gadgets to catch and pokeball various Pokémon, rather than defeating them in battle like trainers do. Some just trap and sell the Pokémon, while others are also trainers.

Their behaviour is seen as unethical/unsporting.

Some, like J, and also the hunter who makes an appearance in the Kalos quest arc of the series, cross the line into illegal behaviour, trapping/stealing Pokémon belonging to others as well as wild Pokémon (e.g. J tying up trainers using her Ariados and using a weird gun to turn their Pokémon into statues so she can capture and later sell them in Diamond & Pearl Ep20, or the unnamed hunter trapping Beatrice's Bidoof in a cage he manages to chew through to escape and later Bonnie's Dedenne in a shock trap/electrified cage in Ep15 of XY Kalos Quest)

An argument can be made that Team Rocket act as Pokémon hunters too.