What is the difference? l am looking to put one in on my 06 WRX, but l do not know the difference. l am looking at the Defi ones, white to match my car. Its basically stock except a SPT high flow intake. l just like the looks of the guages. So, can someone explain the difference and maybe give me a suggestion? Thanks.
l know how a turbo works for crying out loud. l also know what vacuum is. l just what to know the difference between the two gauges.

For the most part it is just in the name.
However a turbo charged car has times when it will be or should be drawing a vacuum. Like at idle. So the best for knowing what is going on is a gage that will indicate vacuum as well as boost.

they are the same. boost is just what it is called when the turbo builds pressure. vacuum is the opposite of pressure or negative boost. the gauge will read both.

they are the same.