The fitting on the left is a rigged 3/8 hose end, the one on the right is swivel. I use a high pressure swivel fitting on the end of my hose only before my surface cleaner.
Yes these top two will screw into one another and that also means I have no need for that darn union that you can never seem to get off. When attaching at the hose reel they swivel so I don’t get my hose all bunched up either.
Hope that helps…….