You will find that there is not much difference in green/ripe bananas in terms of nutritional value, though you will most likely notice a major difference in the way they taste.

Green bananas tend to have a very bitter taste to them, while those which are ripe tend to taste a little better for most people. Green bananas are usually also harder to digest when you eat them, so you will want to consider waiting until they have fully ripened; this process of converting the starch in the banana to sugar which is essentially what ripens it does not take long.

When you wait for your bananas to ripen, you will get the full nutritional value and a much better taste.