Both the recipes contain bananas, and flour. Why is the baking time so different among the two?
These are the things that popped up in my mind at first glance:
How bigger the thing, how longer it will take to be fully baked. This is the reason why you find such a difference in the baking times for banana bread and banana muffins.
The volume can be the same (ground surface x height), but the surface exposed to the heat can differ. If something is flatter, the center is more rapidly reached. If you would bake your bread in a normal bread mold, it would take a longer time than if you would flatten out a bread on a baking sheet (but note that the volume is the same).
Something very obvious. If it's hotter, it won't have to bake as long. However, don't play too much with this. I would advice to use the temperature a recipe has recommended. If you put it too hot, the outer parts can burn, when the inner parts would not be baked fully. This question is related.
Some materials conduct heat better than others. As a consequence, some things will be faster done in metal than in glass for example. (But I believe this has a less important role than the other factors I've mentioned. I can't say much about it, since I don't know a lot about it.)
There are lots of variables, but in this case the answer seems obvious: volume of the product. It takes more time to heat all the big bread than a small muffin.
The other factors that could affect the time include:
Because of the size. The bread is much bigger than a muffin, so it takes longer for the heat to reach the center of the bread. Split the bread to muffin-size pieces and the cooking time will be the same.