briefly from memory (may not be 100% accurate)...
authentique is the basic one, 1.2 8v engine (think it was available in a dci65 too) 14" wheeltrims, tape player, no screen at the top of the dash for outside temp etc, manual mirrors. no rear speakers did have electric windows though.
Expression, 1.2 16v and dci 65 (I think 1.4 16v was available too) as above except they had the electric and heated mirrors, screen at the top of the dash for outside temp display early ones had a tape player, later ones a CD player, also had rear speakers
Privilege , as above not 100% sure on engines but most seem to be 1.4 16v! these came with 14" alloys and front fog lights (seem to be dynamique spec but without the sporty looks and have a less sporty interior.
Dynamique, big range of engines (1.2 16v, 1.4 16v, 1.6 16v petrols and 1.5 DCi 65, 80 and 100 diesels) 15" alloys, front fog lights, bigger rear spoiler, colour coded wing mirrors, inside got a glove box light, CD player (very early Y plates may have had tape players) sporty all black interior with bigger side bolsters on the front seats, silver trim on the dashboard/dials (later ones after 53 plate got silver interior door handles, handbrake button and a different seat pattern along with a front bumper facelift, different wheels (15" version of 172 wheels) and colour coded rear spoilers and also different dials with the larger screen with digital fuel and temp guages). Dynamique also got a trip computer, authentique and expression definitely didn't not sure on the priviledge.
Initiale, 1.6 16v and DCI engines, 15" alloys, xenon headlights, electric everything, climate control, half leather alcantara interior, cruise control etc etc
Special edition models were Billabong and Extreme, bit of a cheaper dynamique so look the same, most don't have aircon, some don't have rear speakers or outside temp gauges, non split rear bench, lower quality head liner etc depending on the year.
Optional extra available...
CD changer
Sat nav
air con
climate control
cruise control
ESP
Cabasse stereo
xenon headlights