Vanguard bolts can be fluted. Remington bolts are a bit larger in diameter so the Vanguard bolts just can't be fluted as deep.
You can use either action and you will be quite happy with the build. The Vanguard actions are close to being perfect in dimensions as is and won't need truing.
I build probably 20 to 1 Remington actions over anything else and have never had a complaint about accuracy. The one exception was a 338-378 on a Mark V action that wouldn't shoot for beans. The problem went away with the change to a different brand of barrel.
