However, to stimulate sexual desire you can actually use orange as a color along with green (for love) with statements such as: "X loves me and desires me sexually very much" or similar.
So to answer you, I personally have always considered love spell as something to have sex with someone you care about (affection or love). While I consider lust as having sex with a person you like only physically. But that's my personal view of the thing.
But orange is good for stimulating sexual desire. Sexual attraction is something you can feel for someone you love or someone you just like physically.