That depends on what you get actually. At level 1, almost certainly. At level 3, it heavily on the parts you end up with.
So if you make a robot at the workshop, it costs you 8 adhesive, 11 aluminum, 9 ceramic, 6 circuitry, and 6 rubber and you get basic protectron parts in all spots (legs, torso, arms, hands and head), then pay additional materials to change the legs, torso, arms, hands and head to something better.
With the Robotics Workshop plot, at level 1 it costs you 16 Adhesive, 22 Aluminum, 18 ceramic, 12 circuitry and 12 rubber and you get protectron legs, then can get robobrain, assaultron, protectron, Mr. Handy, or Sentry Bot torso, arms, hands and head.
However at level 3 of the plot it costs you 10 adhesive, 13 aluminum, 11 ceramic, 7 circuitry, and 7 rubber (about 20% more then base), however you now have a chance at protectron, assaultron, robobrain, mr handy or sentrybot legs, torso, arms, hands and head.
Robobrain, assaultron and Sentrybot legs, arms, hands, torsos and heads have better stats, cost more materials, require perks (that you don't need to have with the plot because a settler is doing the work) and require you find at least one in the wild by killing an automatron before you can make them or finish the mechanist plotline (which you don't need to do to get one via the plot).
Additionally, the plot itself produces materials for making robots MUCH faster then other methods on days when it can't add a part. If you start with no materials at all, you'll end up with a robot generally within 15 game days even if you nothing at all.