A:Answer Hi there, this is Kelly with Dyson. V12 is a smaller, more compact model than the V15. If you have a smaller home or apartment, you may appreciate the smaller size on the V12. This models clear dust bin is smaller in size than the V15, and the V12 is one of the only cord-free models that offers an on/off power button, rather than a trigger you need to hold down to power the machine. V15 is a larger machine, and would have a trigger that you'd need to hold down while in use. Both V12 and V15 offer up to one hour of run time, though V15 will have a bit more suction power, overall.
Best wishes,
Kelly
Dyson Customer Support