EDIT: I've created a separate question to split out the original two questions that were embedded in this one.
Orange dots are active satellites, blue dots are in-active satellites and the purple and pink dots are rocket bodies and uncatagorised, respectively. Its hard to discern the difference between the latter two in colour.
For orientation the geostationary arc comprises the orange dots in a semi-edge-on circle stretching from about "08:30" to "02:30" as we look at the image as a clock face.
There is also a clear ellipse stretching from LEO at 03:00 to an apogee at MEO at about 09:45 and it is made up of a mixture of purple and mostly pink dots. There is another pink ellipse which is completely edge on, on the right hand side slightly above the GEO arc.
When I clicked on objects in these orbits most of them are reported as uncategorised though I did find one labeled as a rocket body part. They are all only in the Vimpel catalogue and not reported as having USSpacecom IDs.
It looks like these two arcs might be debris from a rocket body fragmentation; the separate question mentioned above asks what the causing event might be.
The question, finally: Are there really this number objects that are observed by one system, Vimpel, but not another USSpacecom? Why is this?
These objects would be close enough to Earth to be visible to radar at perigee and high enough, and thus slow enough, to be tracked optically at apogee, so LEO Labs and Exonalytic should also have an opinion.
EDIT Following PearsonArtPhoto's analysis and info (see his answer here and then trace it to the paralellel question I raised on the cause of the apparent fragmentation) I looked up the object he mentioned (USA 257, satcat 46653, COSPAR 2014-055DD) and came across this report from ODQN which suggests that the parent object is indeed a Centaur upper stage, 2014-055B:
The fragments in the Gabbard plot to me look more spread out in altitude than those in Astriagraph, though its hard to tell. However the main thing I have learned from this, and a bit more experimenting with Astriagraph is that you can switch out populations of objects and discover that pretty much all of the uncategorised objects and a few of the inactive satellites are from the vimpel catalogue and all the rest are from USSpacecom, there may not be much overlap at all. For the moment I think my question remains as originally asked, though I am curious to understand more about the purpose of the Vimpel list.