i think it has something to do with the possibilities of it happening..."yo quiero un gato, yo quiero ir a la playa", because i'm probably gonna do it if I really want to, but "yo deseo un billón de dolares, yo deseo tocar una estrella", i think desear goes with something you dream of but that's hard to get :)
My daughter wants a horse or my daughter wishes for a horse ... the difference ? The fault ?? Come on, Guys !