Compatibility of pressure gauge with valve
There are Presta, and Schrader valves. There are also dunlop valves but they are far less common these days, especially in the US/UK.

Schrader and Presta are two different diameters and valve types. There are pumps that will inflate either, there are also pumps that only inflate one or the other. Many people use a pump with a built in gauge rather than carrying an independent gauge. There are however gauges that will also read both valve type, they generally have two different heads, one for each type of valve. 

Such as this one:



One side is for Presta and one is for Schrader. A presta will not work on a schrader and vise versa.