Many resources show simple interest as i = Prt and compound interest as A = P(1 + i)n
BUT it may be easier to compare if we look at formulas for calculating amount for both interest types:
A = Amount, P = Principle, r = interest rate (%), n = number of interest periods, t = time
Simple Interest: A = P + Prt or Compound Interest: A = P(1 + r/n)nt