Yep. Very big difference.
The fact that I barged in on her without her knowing, as she was about to get dicked down, doesn't change the fact that she was about to get dicked down either way, even if I hadn't shown up.
If you ride shotgun with me in my car, we're sharing a ride. If you take my car without asking me first, to take it out for a spin by your own, without me ever giving you permission to take my car keys whenever you like, I didn't share a ride with you, you stole my car.
Anyone who doesn't see the distinction, please tell me where you have your car parked, so we can "share".