Same thing, its when the roots are not able to take in all the nutrients because its being overloaded. Think of it like a washing machine, putting more than directed soap amount may seem like a good idea but it won't wash your clothes because there's too much. It just can't absorb all of that...
Mars hydro is the best bang for the buck but also the Philzon is cheaper and is getting a lot of hype. Both are on Amazon. I have the 600w marshydro for veg over 2 girls but will need something stronger for flower if I want to yield a high amount.