Gamma
What a mess with all those different types of Peugeots. For quite a while the 204 and 304 have been produced at the same time, but the 304 seems to be a more modern follow-up of the 204. If anyone can tell me why that has been done, please let me know and I will spread the word (on the internet)!
Anyway, how the modelrange has developed through the years can be seen in the schedule.

Nice pictures are available when clicking on the modelname.

YearModel/typeEngine
spring 1965204 Sedan1130 cc gasoline
autumn 1965204 Break1130 cc gasoline
1966204 Convertible1130 cc gasoline
1966204 Coupé1130 cc gasoline
1967204 Van1130 cc gasoline
1968204 Break1255 cc diesel
najaar 1969304 Sedan1288 cc gasoline
voorjaar 1970304 Convertible1288 cc gasoline
voorjaar 1970304 Coupé1288 cc gasoline
najaar 1970304 Break1288 cc gasoline
najaar 1972304 S Sedan1288 cc gasoline
najaar 1972304 S Convertible1288 cc gasoline
najaar 1972304 S Coupé1288 cc gasoline
1974204 Break1357 cc diesel
najaar 1974204 Sedan1357 cc diesel
spring 1976all 204-models
spring 1976all 304-models1290 cc gasoline
spring 1976all 304 S-models1290 cc gasoline
autumn 1976304 Sedan1357 cc diesel
1977304 Break GL1127 cc gasoline
1977304 Break SL1290 cc gasoline
1977304 Break GL1290 cc gasoline

(Please don't be angry when the list is not complete or correct)

As said and again visible in the schedule, the 204 and 304 were produced at the same time. Differences like the shape and a more powerful engine are the most notifiable. The more modern shape of the front (especially the headlights), rearlights and interior are directly visible. The engine got more cc's (the 204 has 1130cc and the 304 obtained 1288cc).

I almost forgot to show you the productionnumbers of the Peugeot 204 and 304 range. Here they come:
(Now you can check if you have a rare Peugeot!)

ModelAmount
204 Sedan1.020.029
204 Break485.336
204 Convertible18.181
204 Coupé 42.756
204 Delivery van37.994
304 Sedan849.103
304 Break216.183
304 Convertible18.647
304 Coupé60.186
304 Delivery van34.304

The production of the 204 convertible and coupé is stopped during spring 1970 and were replaced by the 304-series. These little sportscars have been produced until 1976, like all the remaining models of the 204-series. In 1976, the government sharpened the emission-regulations and so most engines were replaced bij cleaner ones. The Peugeot 304 has been sold until 1979.