The primary influence of energy deliverable by pyrotechnics, propellants and explosive is burn rate.
As the burn rate changes, so do the products of the combustion.
The forms of energy delivered are heat, gas and light, depending on the material or combination selected. Pyrotechnic compositions produce intense heat and often intense light with very little gas production.
Propellants are used to deliver high- pressure volumes of gas, often with only moderate heat.
Primary explosives rapidly (microseconds) develop hundreds of thousands of psi of gas pressure, while high explosives develop millions of psi in even a shorter time frame, with very little heat production.