Pool owners and even manufacturers often interchange these terms. All pool covers help retain heat, so they are also "blankets". Furthermore almost any pool cover will help collect heat from the sun, hence it acts as a solar cover

Pool covers do half the work by simply keeping leaves above the pool water. Once on top of the pool cover, leaves will often blow-away. Occasionally using an ordinary garden blower provides an instant solution. You should of course wait for "dry conditions"