The color doesn't make any difference with how the gloves function. The color is aesthetic or in some cases, organizational, e.g. green for food handling and blue for medical.

Nitrile gloves come in different thicknesses, which changes how strong they are and how tactile. For food handling, the thinnest 2-3mm is usually fine; you still get good feeling through them and they're cheap so you can swap them out to avoid cross contamination.

If cutting fish, you may want slightly thicker gloves, like 4-5mm or 6-7mm, so they hold up better. But if solely for smell/fluids contact, the 2-3mm should do you.