Hodgdon slapped their label on 700X and the other powders made by IMR/Expro/General Dynamics of Canada only a few months ago. They are leaving the IMR brand on the actual Improved Military Rifle powders inherited from DuPont in the 1970s.
Hodgdon does not make any smokeless powder and do not own the powder mills serving them. I am not clear on how they get Pyrodex and 777, maybe they have production lines, maybe they have them toll manufactured. Oh, yeah, they also bought out Goex for the real black powder capacity.
I have a little different understanding of the rest of the situation than Marco.
St Marks (General Dynamics, was Olin-Winchester in Florida) makes all the Winchester Ball powders and Hodgdon Spherical powders. Also some of the Accurate Arms ball process powders.
IMR (General Dynamics, was Expro, in Canada, was DuPont in the US) makes most of the extruded powders under the IMR label and 700X, 800X flake powders now called Hodgdon. There are still some discontinued SR 4756, 4759, and 7625 and some PB-6 powders under the IMR label.
ADI (Thales Australia) makes the Hodgdon extruded powders and for some strange reason "IMR" Trail Boss. The situation with H and IMR 4227 and 4198 is confusing, I don't recall who makes what for whom but it is not necessarily what it looks like.
Accurate Arms and Ramshot (both now owned by Western Powder) import a good deal of their powder but get some of it from St Marks.
Alliant Powder (Hercules to us old timers) makes the shotgun and pistol powders from Red Dot to 2400 but imports the Reloder rifle powders from various sources in Europe.