Looks like you have the adapter thingy that allows use of the head with both screw sizes. This probably comes as standard with the Manfrotto heads. It may be I was thinking the other way round that you can't put a Velbon head on a Manfrotto leg set unless you have more adapter thingies.
It was handy to mention as I had assumed that all fittings were standard so it made me check and make sure before I bought something I then couldn't use
I do recall the adaptor ring did come of the manfrotto monopod but it seems pretty well secured so I might have imagined that!
In my experience, all heads fit all tripods. Some tripods have the clever spring loaded threaded sleeve over the narrower thread.
Some heads have an unscrewable threaded insert. It is easy to miss both on a casual inspection.
Well I got a second hand toilet tent.
Her ladyship wants me to cut 8" off the legs, and then she will sew up some old camo sheeting and stitch in assorted zips to make me a lovely portable hide for bird photography.
Can't wait.