NEMA 6 and NEMA 6P Enclosures is a waterproof enclosure or submersible enclosure. So you can submerge it under water.
How are they different from each other? find out more from our articles.
NEMA 4 and 4X enclosure is a weatherproof enclosure, cannot be submerge under water. However they provide protection against direct water hose.
Server rack cabinet can be manufactured adherence to many types of NEMA enclosure, such as NEMA 4, 4x, 3R, 12 even from NEMA 6 or NEMA 6P enclosures.
A/C or Climate controlled enclosures can also be manufactured adherence to any type of NEMA enclosures depend on the environment that it will be put in.