the boxy shape one is a mk1 coming in ph1, 2 and 3.
the rounder shape is a mk2 coming in a ph1 and ph2
the new shape is a mk3 and there is only the 1 shape as of now
the sports are totally different
the 172 comes in tow shapes, ph1 and ph2
the 172 ph1 is the rounder headlights the same as the mk2 ph1
the 172 ph2 is the facelift headlights the same as the mk2 ph2
and the 182 the same as the 172 ph2 with an uprated exhaust system and other things (im not quite sure) giving it 182 bhp. it is not known as a ph3 just plainly as a 182.
and the 197 is obviously the mk3 sport version and is only known as a 197