Very close in person.
(other than trunk & displacement, haha)
Wheelbase:
s2000: 2400mm
fiat: 2310mm
Width:
s2000: 1750mm
fiat: 1740mm
Height:
s2000: 1285mm
fiat: 1233mm
Curb weight:
s2000: 1274kg
fiat: 1070kg
Engine:
s2000: 1997 cc , 237hp
fiat: 1368 cc , 164hp
(Warning, wikipedia data)