This is a very vague post. You need to provide more information. Take note that most bettas tend to spit out their food when they are introduced to a new environment. There is no correlation between your betta's color and their eating habbits.
Specifically, what kind of food are you feeding your bettas? One fish died...... not much info there. ...... really need you to provide information if you want answers.
Yes bettas vary greatly in their appetites.
On the other hand, there is a great coincidence in the fact that my red betta is very picky as well :))
He only eats bloodworms and would snub anything else i put in his tank.
Goodluck in finding the right food for your betta! :)
I think my solid red eats better than the dark blue but they both eat well. It may be that whatever you are feeding them just suits one fish more than another. I am almost certain that color has nothing to do with it.