What is the difference between a Torpedo Studio and a Torpedo Live?

The comparison chart here will give you the technical differences:

Two notes products Comparison Chart

Sound-wise, the differences will have to do with:

• the type of loadbox (reactive for Live , or reactive / resistive + load compensation for Studio);
• The Torpedo Studio is multi-impedance (4, 8 or 16 Ohms);
• the presence of Overload and Variphi on the Studio;
• Non-linear convolution on Studio, not on the Torpedo Live and C.A.B., meaning the speaker breakup is modelled;
• Highest-grade analogue and digital electronics on the Studio (the technology involved in the Live and C.A.B. is slightly lesser, although it does remain very high-end).

To sum it up, the devices will sound differently, but they are all state of art. What you will need to consider is your own preferences and priorities — price, esthetics, functions, etc... If you aim at the best possible speaker simulation for your recordings, the Torpedo Studio is what you need.