http://prius.toyota.com.au/toyota/vehicle/FreeText/0,4665,2382_842,00.html

In Australia, the Prius has only 2 option packages, the base model and
the i-Tech (loaded) model.  Base model has the cruise control and EV.
i-Tech package (for 2006) adds the rear view camera, Bluetooth, JBL
audio with 6CD changer, Smart Entry & Smart Start, side air bags, VSC,
navigation, audio aux-in minijack.

(Similar naming convention in New Zealand, as well, but the i-Tech
package doesn't include navigation there.)

It's just easier to use the Toyota option package designation to
describe your Prius, rather than having to list all the stuff that is
on your Prius...

In the US, for 2006, there are 8 option packages, not including a base
model with no options: http://www.toyota.com/prius/options.html  (GY,
HE, HF, HG, HI, HK, NL, NW).  For 2005, there were 5 option packages,
(GY, AG, AI, AM, BC).  For 2004, there were 9 option packages, (RW, GY,
AF, AG, AI, BI, AM, BG, BC).   The items included in the option
packages are the same for the same option package codes.
See also:  http://www.hurtley.org/PriusPackages.png  for comparisons.

In Canada for 2006, there is the base package, and then option packages
B and C.

In the UK for 2006, there is the T3 (base, no cruise control but EV),
the T4, and the T-Spirit (loaded model).  I know that there is another
country that uses this same naming convention, but I don't recall which
at the moment...

In Ireland for 2006, there is the "Luxury Pack" or the "Navigaton Pack"
for your Prius, besides the base model.

In South Africa, there is only one model Prius.

In Italy for 2006, besides the base model there is the "Navi Pack"
which adds cruise control, navigation, Bluetooth, and Integrated
Parking Assist.