Depending on their temperature, stars differ in their colors. Although it sounds a bit counterintuitively, colder stars emit "warm" yellow light, whereas hot stars emit "colder" blueish light. Although it's not always that easy to see this color in photos, taking a photo with the lens out of focus makes the colors very clear, as can be seen in the example below.
[ in focus || out of focus ] ⇛ Orion. (2016-02-29)
Six photos (each with slightly different focus) combined into one, to make the colors clear. Most stars look blueish, but Betelgeuse in the upper left clearly has a yellow/orange color. The "star" under Orion's belt which looks a bit reddish is in fact not a star but the Orion Nebula (2016-02-29)