Just read some more descriptions on the adorama site it would appear from their specifications that the Glossy RC product is Kentmere compare the 2 statements below:
Adorama VGRC is a high speed, variable contrast, black and white enlarging paper with a medium weight, polyethylene coated base. The paper base is 190 g/m2 coated on both sides with 40 g/m2 of polyethylene giving a base weight of approximately 270 g/m2 and a thickness of approximately 245 microns. The silver halide emulsion has a silver content of approximately 1.5 g/m2.
From the freeswtyle Kentmere specs:The paper is 190 g/mē coated on both sides with 40 g/mē of polyethylene giving a base weight of approximately 270 g/mē and a thickness of approximately 245 μm.
Coated emulsion layer
The light-sensitive silver halide emulsion layer has a silver content of approximately 1.5 g/mē. This is covered with a gelatine supercoat which protects the emulsion from stress fogging and physical damage and also contains a developing agent.
I also checked out the adorama FB VC product and its description matches the edu ultra/foma paper i.e. they are the only paper descriptions I have ever seen calling themselves ISO 9001 certified the rest of the descriptions pretty well track also.
So this seems to be the reason that folks on other threads notice speed differences between different adorama papers i.e. FB and RC