I didn’t know it had changed – AFAIK, you could still be done for “speeding” on a bike.
Appears to still be the case, The Royal Parks and Other Open Spaces Regulations 1997, amended by Statutory Instrument 2004 to be “On the Park roads in Bushy Park, Greenwich Park, Hyde Park (except for the Serpentine Road), The Regent’s Park, and St James’s and The Green Parks, at a speed not exceeding 30 mph, and on the Park roads in Richmond Park, at a speed not exceeding 20 mph”
Not sure if the bike track is a “road” for these purposes, but you are required to follow instructions given by notice.
To answer the OP, I would say neither, they are royal park roads subject to specific, and quite different regulations, eg no trade vehicles, no caravans etc etc