Thirst is driven by the unpleasantness of dehydration, while hunger is more about the reward of food.

“when you stimulate these neurons that make an animal thirsty the mice hate it they will do anything to avoid something that artificially makes them thirsty so we can artificially stimulate these thirst neurons create a state of virtual thirst um they'll lever press hundreds of times to make it stop the same neurons that the neurons I talked about that control hunger the arrp neurons they actually don't so much um they won't really do much of anything to shut them off that raises the question why do the animals eat then when you stimulate the hunger neurons and we think the primary thing that the hunger neuron stimulation does is it make food itself more attractive it makes the food more delicious more of an attractive motivational magnet it makes the experience of eating more pleasurable but it is not itself the most unpleasant State at least the mice aren't willing to do that much whereas for thirst I think you know dehydration and thirst is really just unpleasant and animals just want to avoid that and so I think that distinction is is is very real”