Modern dishwashers have to use less than 5 gallons of water for a normal load. To get the Energy Star rating, that has to be 3 gallons.

A typical two-basin, 33 inch kitchen sink, each basin measures 16in x 14in. Each inch of depth in each basin is approximately 1 gallon. To fill up both basins to a depth of 5 inches, that would take 9.6 gallons, more than 3x more than an Energy Star dishwasher.

So yes, significantly.