potassium nitrate (KNO3) and potassium phosphate K3PO4 are two potash fertilizers which one of them is better fertilizer
Potassium phosphate is known for chemical property, safe usage and non-toxic behaviour. This fertilizer is effective nutrient for plants and makes them healthy and improves their growth.
Whereas, Potassium nitrate is not only used as fertilizer but also for model rocket propellant, various fireworks and smoke bombs.
Both fertilizers are good but phosphate one is more focused on plants