Howa's are a more polished blue vs Vanguard's bead blasted matte finish.
Gas vent holes on the bolt are on the bottom of the Howa vs side of the Vanguard.
Different bolt should and primary extraction on them, both work well.
Howa's usually come in a Hogue stock with free floated barrel, Vanguard uses a stiffer synthetic stock with a pressure point on the barrel.
I have a few of both, the Howa's shoot ok in the Hogue stocks, but the Vanguard's always seemed to shoot a bit better with the stiffer stocks and pressure points. All my Howa's are now sitting in Vanguard stocks (couple Vanguard's are now in B&C stocks as well) usually can pick them up cheap off the EE.
They are both big beefy actions, fairly heavy rifles, I find them better suited to long action cartridges with heavier recoil due to this, they match up well together.
This kid of shows the difference in finish, as well as a pic of the hammer forged bores...pretty smooth.