No, the necks of a Fender Jazzmaster and a Fender Stratocaster are not the same. While both guitars are made by Fender and share some similarities in design, the necks on each guitar have distinct differences.
The Jazzmaster has a wider and flatter neck profile, while the Stratocaster has a thinner and rounder neck profile.
Also, the Stratocaster typically has a shorter scale length than the Jazzmaster. These differences in design can affect the feel and playability of the guitar for different players.