And something implied in Denti's answer, but to state it explicitly - because the ground spoiler function wants as much lift dumped and drag created as possible, ground spoilers are (always - I bet someone will prove me wrong though) designed to either be stowed or fully deployed. there's no point in having "half ground spoilers".
Flight spoilers are intended to be a variable control, where you can command any of a range - perhaps a continuous range - of positions to get the amount of drag you want.
Its a lot simpler to design a ground spoiler control, as a result, than a flight spoiler. And thus cheaper. So you don't make them the fancier "flight spoiler" type (or even fancier spoileron type) unless it's required.