Why does laser beam might appear blue and another laser beam might appear red?

One thing about a laser is that the light it puts out is all one single sharp

color (wavelength) of light with no other wavelengths mixed in with it.

That wavelength is a different one for the different kinds of material

that are used to do the "lasing" ... generating the light. There are a

couple of different wavelengths of infrared lasers, and several different

types of lasers in the visible range.