Quick comparison
Both appeared in 1947. Both have a V12 engine, mounted at the front. The higher top speed belongs to the Ferrari 125 S: 210 km/h versus 180 km/h. The lighter one is the Ferrari 125 S: 650 kg versus 750 kg.

Both appeared in 1947. Both have a V12 engine, mounted at the front. The higher top speed belongs to the Ferrari 125 S: 210 km/h versus 180 km/h. The lighter one is the Ferrari 125 S: 650 kg versus 750 kg.
All values come from the data sheets of the two models (sources listed there). The better value is highlighted in green wherever both data sheets give a comparable figure. Photos – Ferrari 125 S: Christine und Hagen Graf from Fitou, France, CC BY 2.0. Licenses and originals: Sources & image credits.