What happend to all the business people?!?

[mindflayer]

Here is a detailed question then..

I have researched 40' containers and found that there are various types.. open top, flat rack, refrigerated units..
and
the standard 40' (dry fright) container
and a 40' (high cube) container.
The research only shows a general size (height) difference, but does not say when you would use one over the other.

Do you know of any restrictions/regulations or general reasons for using one over the other?!?