The Hawk Droid was an attempt by the Trade Federation to improve upon the faults of the Vulture Droid in the early months of the Clone Wars. It was designed for superior speed, maneuverability, and artificial intelligence. Its smaller, sleeker design reduced the cost of raw material, although more competent AI was more expensive than the Federation anticipated. Only a few hundred were produced and they were deployed to a small number of Outer Rim worlds, where they performed far better than Vulture Droids at an individual level, but overall the financial impracticality of mass-producing them convinced the Federation to end production of the Hawk Droid.
As the title says, and the in-universe description implies, the Hawk Droid is built exclusively from parts of the Vulture Droid, set 7111 from 1999. I might add instructions if anyone's interested.