You understand what supply side economics is, or difference between fiscal and economic policy.
I find it facinating that in libtard lexicon, "supply side" is a perjorative. Part of rewriting Reagan, Clinton and Bush's legacy I suppose.
The theory behind supply side economics is unlike in Keynsian models, you try to move the supply curve, by increasing investments. You do this lowering taxes on capital so it will theoretically make people want to invest their capital in businesses therefore increasing productivity which in theory would move the supply curve down.
Another component of supply side economics is fiscal responsibility as a high national debt should raise interest rates and therefore making it more attractive for people with capital to save money rather than invest that capital in businesses.
Did I answer you question satisfactorily for your tastes or would you like me to go on?