Yup, different purposes. Ambulances drive up to factories/offices, you only maybe need to get someone stabilized enough to move them out of the building, and if not a life threatening issue, to their car so they can go home. More serious issues, you get some full time medical personnel to fix it for you. OSHA rules are odd regarding what you are allowed to do, what paperwork means what etc. I would /guess/ (but get a lawyer for this if you have a factory) that this falls under some treatment threshold as well whereas the big one does not.
FYI re context: I carry on me a cut-in-half standard SAM because our training ground stuff is similar. If a serious injuy, we'll just keep them alive but call for help with ATVs or helicopters (and back in the admin vehicles there is a big FAK with stuff like full size splints). We self-evac lots of sprained (or broken!) ankles, so that's enough to get those folks out without too much delay or inconvenience.