Not that pantsers are somehow organic and spontaneous while outliners are staid and rigid.
No, the difference is that Planners can leave the plan. They are able to just busk away from their outline whenever they need to.
Pantsers (and I can only really speak for myself here) can’t do that. We take the plan as The Plan and have to follow it. Therefore we don’t plan and hence we don’t have to follow it.
PK’s Caveats: Caveat 1: I may not know what I’m blathering about. Caveat 2: There are no rules about writing, there are just things you can get terribly wrong. Caveat 3: If people apply the words never or always to storytelling techniques, ignore them.