R99 is the original standard for UMTS WCDMA based networks. HSDPA is an add on to R99/UMTS networks which adds a shared high speed downlink packet channel. There is a partner to HSDPA for the uplink known as HSUPA (High Speed Up Link Packet Access) or EUL (Enhanced Uplink) as well which can boost uplink speeds to at least 1.9Mbit/s and I believe higher (but I cant recall the highest speed it can do – I think it is 7.2Mbit/s).
R99 supports CS Voice/Video and PS up to 384Kbit/s DL/UL. HSDPA with Class 10 devices can support on a shared channel up to 14.4Mbit/s.
All of this is carried on Wideband CDMA Channels. Further reading can be seen on the 3GPP standards website.