Coconut butter is best thought of as a condiment or a spread like almond butter.
You can use it in cooking but not necessarily to cook in.
Coconut oil, on the other hand, can be used like any other cooking oil.
For ex. I have slathered coconut butter on chicken thighs and baked them in the oven, mixed it with melted bakers chocolate for "mole" chicken, and it factored heavily in my 5-layer bacon bars.
I've tried several and I've found them all to be the same. I like Tropical Traditions Coconut Cream Concentrate (same as coconut butter) because they often offer it buy one, get one free :) Coconut butter can't be used like oil for sauteeing and such, but it's great stirred into curries. A lot of people like eating it by the spoonful, but I find the texture to be a little too gritty.
From the part of your question where you ask about cooking with it, I think you are asking about coconut oil, am I right? Coconut oil is an oil pressed from the coconut meat, used for cooking, skin care, etc. Coconut butter is a nut butter made from the whole coconut meat, the same as almond butter is made from whole almonds. I usually use Aunt Patty's coconut oil, because it comes in glass jars, and is reasonably priced where I live, since the processor is fairly local. I use Artisana coconut butter because it's divine, and a jar lasts me a long time, so I don't worry that I am paying nine dollars for a jar...it's a treat for me.