Economically, there are major differences in who pays them, There are differences in impact/cost. There are also huge moral differences between subsidizing desired behavior, and penalizing undesirable behavior.
It'd result in more people eating better though (instead of just eating slightly less worse, or eating worse differently while still not getting enough healthy food) and so there'd also be savings in the cost of health care and improvements in productivity.
Taxes and benefits are extremely unequal in their application.