Is white slice bread or brown whole wheat slice bread more in calories? How many calories does one slice of white bread have and one slice of brown bread have?

There is room for plenty of variation as far as the number of calories that you are going to get depending a quite a few factors. I would suggest checking out the information on the following site.

Calories in Bread

The white bread has more additives and less nutritious because of the fiber and more nutrients therefore it is easier to digest in the long run.
Look for "Whole Grain" or "Whole Wheat". If bread is labeled “Wheat Bread”, this does not mean that you get more nutrients.

The "average" brown bread has approximately 82 calories a slice, and white has around 100 calories a slice. Read all nutritional labels to see exactly how many calories and what ingredients are actually in the bread your eating.