The basic difference between the two paints is that latex paint is water-based and acrylic paint has a chemical composition that gives it elasticity. (Just to confuse us all, there are "acrylic latex" paints, with varying degrees and properties of both.) Outside house paints are moving away from latex to 100 percent acrylic because the latter easily expands and contracts with heat and cold. As a result it holds better than latex. You are right-there is a difference in price. Latex paint is much less expensive, but remember that if you use latex over the more expensive acrylic, the surface will have to be painted again much sooner.