What is the difference between GPRS, HSPA and HSDPA?

Question

In wireless communication we use the above services to access the internet. What are the differences between the above technologies. I know that there are differences in speeds but I expect some statistical information or technology definition like thing. I mean a good comparison :)

Update :

I am adding the thing I realized..

HSPA is a common term that used to group 2 technologies. HSDPA and HSUPA. They are operated in UMTS networks.

GPRS works in GSM networks

Answer 1

GPRS or Generalized Packet Radio Service is generally associated with 2G networks and provides data rates of 56-114 kbit/s.

HSPA or High Speed Packet Access describes a family of related cellular data protocols.

HSDPA or High-Speed Downlink Packet Access is a particular HSPA protocol and currently provides for speeds of 1.8, 3.6, 7.2 and 14.0 Mbit/s.

Answer 2

Wikipedia page for HSPA mobile telephony protocols
A Short comparative-description page reference.
AT&T reference page.