Picante sauce is spicier than salsa. It's usually made with chili peppers whereas salsa is usually made from tomatillos, peppers, and tomatoes. Sometimes picante sauce is added to salsa to make it spicier.
Logan is correct (I love that cow avatar) and I'll add that picante sauce is usually much thicker than your standard salsa. Picante sauce has larger chunks of easily identifiable vegetables.
Could we also say that Picante sauce has ingredients that have been cooked while salsa's are raw? Just like @Amanda says, Picante is usually thicker and chunky.