Each galaxy gives off its own spectrum of light. The spectrum includes colors and thin black lines. The dark lines are caused by the elements in the sun absorbing some of the light the star emits. If you are comparing 2 stars, what would it mean if the colors were shifted to the right of the spectrum?

Question

Each galaxy gives off its own spectrum of light.  The spectrum includes colors and thin black lines.  The dark lines are caused by the elements in the sun absorbing some of the light the star emits.  If you are comparing 2 stars, what would it mean if the colors were shifted to the right of the spectrum? 
What would it mean if the colors were shifted to the left of the spectrum?