I highly advise that you gradually add the powdered or crushed red pepper flakes to your recipe. Start with one-third of a teaspoon for every teaspoon of paprika. Give it a taste to check the heat and spiciness, and add more when needed.
Red paprika has a sweeter and milder flavor. It may be smoked, which will give it a different flavor altogether. Additionally, Hungarian sweet paprika is milder than Hungarian hot paprika. The hot variety can be hotter than jalapeno. Spanish paprika comes in mild, medium and hot variants.

