I’ve always bought light red kidney beans for chili.
What’s the difference between light red and dark red kidney beans?
Is one a more ripe bean compared to the other?
What’s the difference in taste or texture?
I’ve seen dark reds in three bean salad. But otherwise I’m not sure what else they’re used in?
Color. I kid.
The dark red ones are better in salads like you’ve seen. Or otherwise cold. I find the light ones bitter.
There are many, many colors of peas and beans. I think it’s all what youre used to.
I seem to remember (decades ago) there used to be only one choice. I bought a can of kidney beans.
At some point, cans of light red and dark red appeared on the shelves.
I usually buy the light red, but once in awhile the other can gets in my cart. Chili has so many spices that subtle differences in the bean isn’t noticeable.
I use pinto beans in chili. I’ve only used kidney beans in salads.
There are hundreds of varieties of beans. Go to the Rancho Gordo website if you don’t believe me. There are subtle differences - could you tell navy beans from black beans, in a blind test?
But it’s not like using the “wrong color” of bean will screw up a recipe.
I thought maybe light red kidney beans were less ripe than dark red. That might effect how strong they taste.
Turns out they are two different varieties of beans.
Navy beans vs white beans are another example. Both are good. 
I like most beans that I’ve tried.
https://www.ehow.com/facts_5791272_dark-light-red-kidney-beans.html