IMHO both use the same engine there are differences in the gear ratios . December 2000 Car magazine 330i 5 speed road test :speeds at 6500 rpm , 1-61 , 2-104 , 3-155 , 4-209 , 5-259 ,doing 39.8 km/h per 1000 revs .gear ratios : 1-4.21 , 2-2.49 , 3-1.67 , 4-1.24 , 5-1.00 with diff 2.93 .
Car mag Sept 2003 : 330i 6 speed . Speeds at 6500 rpm : 1-57 , 2-98 , 3-148 , 4-200 , 5-246 , 6-289 with 6th at 44.54 km/h per 1000 revs . Gear ratios are 1-4.35 , 2-2.30 , 3-1.66 , 4-1.23 , 5-1.00 , 6-0.85 with 3.07 diff ratio . Both had 225/45 x 17 tyres .5 speed did 250 in 5th at 6277 rpm , 6speed did 255 at 5726 revs .
Hope this helps .