The Weatherby Vanguards are built by Howa and they just stamp Weatherby on them instead of Howa. Weatherby does have some slightly different specs but I'm out of the loop as to exactly what they are presently.
At one time Weatherby's all had 24" barrels. Howa used 22" barrels on some, 24" on others. The stocks are usually slightly different but will interchange. The safety used to be slightly different and Weatherby used to flute the bolts whereas Howa did not. But all of the parts will interchange. Anything you read about a Weatherby Vanguard applies to the Howa. Other than some minor differences in specs they are the same rifle.
Generally speaking, they are very well-made rifles that tend to be above average accurate. The bare action is one of the heaviest, so the rifles tend to be heavy. Since it's the action that has the weight it's hard to make them lighter. Thinner, shorter barrels and lightweight stocks only do so much.
MOST scope mounts made for a Remington 700 fit both Howa and Vanguard. The exception is if you're using a 1 piece base on a short action. Remington and Weatherby have different hole spacing. Long actions are the same with all 3 rifles and if you're using 2 piece bases the ring spacing doesn't matter so those intechange.
At one time you could get a Howa quite a bit cheaper than a comparable Weatherby, but that's not always true anymore. At times I've seen Weatherby's sell for less than a comparable Howa.