basically run time and accessories.
the dc35 runs for about 13-15 mins on a full charge in regular mode and 5-6 mins in turbo mode.
the dc44 runs for about 18-20 mins on a full charge in regular mode and about 8 mins in turbo mode.
the dc44 also includes an extra accessory tool called the 'mini motorized tool', which works great for picking up pet hair and vacuuming upholstery.