There are two basic types of grapples usually discussed, then variations of each. An L bottom grapple is often used for hauling debris and digging down to get rocks and roots out if the grapple is narrow enough. A Rake grapple has shorter lower teeth intended to "rake" out shallow roots and clear brush. I have both and use my rake for brush and back raking (yesterday and today I have been back raking brush and limbs away from a creek). I rake the brush back in a row a few hundred feet of creek edge, then swap grapples and scoop up the debris with the L bottom which grabs more and makes for less trips to the burn pile. I attached pictures from theWR long website of an L bottom and a Rake. The third is sort of a hybrid Rake with longer lower teeth which would be useful in hauling.
