The difference in taste between white and brown bread is significant, as is the texture and obviously the way it looks. When you are brought up on white bread, it can be really difficult to make the change.
There's some other things you might like to point out about white vs. brown as sometimes the words "because it's better for you" just don't cut it with a white bread addict:
White bread is made is from wheat flour from which the bran and germ have been removed. This is where much of the nutritional bread value is. White bread is lower in zinc, fiber, thiamin, niacin, trace elements and "good" fats and oils. White bread in many countries has to be fortified with vitamins and minerals *by law* during the bread making process. These are usually sprayed into the mix. It's somewhat ironic that the nutrients that are removed from wheat are re-added by this means. Nature provides, we destroy, then add it back in via a man made form.
Once the bran and germ is removed, the flour is bleached using potassium bromate, benzoyl peroxide or chlorine dioxide gas. Potassium bromate is also known as Bromic Acid or Potassium Salt. It's an oxidizing agent, can be fatal if swallowed, is harmful if inhaled or absorbed through the skin and may also cause kidney damage. Benzoyl peroxide is another irritant that can kill animals, birds, or fish, and cause death or low growth rate in plants. Chlorine Dioxide is also a pesticide and even though it breaks down very quickly, it is ranked in the USA as one of the compounds most hazardous to the environment.
So even before the baker adds his chemical magic, there's some pretty solid cons relating to white bread. Another point to note is that anything that needs "refining" requires more energy resources to do so.
By the way, just because bread is brown in color doesn't necessarily mean it's brown bread in the traditional sense of the term, i.e. meaning whole wheat or wholemeal. Check out the ingredients on the bread that you buy and ensure that the first ingredient is whole wheat or wholemeal flour rather than enriched wheat flour or just wheat flour. Enriched/wheat flour is the same type of flour used in white bread. The presence of caramel also is an indicator that it's not true brown/wholemeal bread as caramel is used as a coloring agent. A couple of other ingredients to avoid if possible are fructose corn syrup and partially hydrogenated oil/fats; aka trans fats.
The general rule of thumb is the less ingredients in the bread and the presence of wholemeal flour as the major ingredient, the better it is for you - and the planet