Lowes has a big selection on Whirlpool water heaters. Some of them
are called 'Tall' water heaters and some are just plain old water
heaters. However, the only dimensional difference I see between the
'Tall' and 'standard' is in the diameter. What is up with that?
The 'Tall' water heaters also seem to have a slightly higher energy
factor (about 10% higher). I assume that's because they have more
insulation (contributing to the larger diameter).....?

Any anyone shed some light on this for me?