The 1750, especially a series 1, is a much prettier car in many details - interior and exterior - not just the grille. There is the best steering wheel, the most beautiful dash, prettier early Carello headlights, nice small taillights, standing pedals (In Aus they all had them), prettiest seats, etc. The engine is sweet and powerful enough. However the car definitely lacks an LSD, though that was a special option.
The 2000 is definitely quicker and has the LSD. It will cover ground more quickly than a 1750 because of additional torque and the LSD but the 1750 puts a bigger smile on your face. A lot more plastic ... a beautiful car on its own, especially Euro spec but clearly not in the same league with regards to looks as a 1750GTV.
Engines: a 2000 can be made to be quite sweet but the combination of heavier fully counterweighted crank and offset combustion chambers probably will not allow it to be quite as sweet and quick revving ... though the nitrated crank is definitely a bonus.