Panasonic Power Tools & Cordless Tools

Is there a difference in work capacity between tools with different voltages?

Yes, with exceptions. Within a manufacturer's line of tools, where all other technology is equal, a higher capacity battery can perform more work. For example, a Panasonic 12 volt drill can outperform a Panasonic 9.6 volt drill on the market based on design, motor speed and other technical specifications.