1.) See IEEE Paper PCIC-97-5. It is a bit outdated now with the European Union’s (EU) introduction of the ATEX directive, but it still covers the essential differences. The ATEX directive primarily affects the marking systems of equipment, but not the determination of Electrical Area Classification.
Originally Posted by pubdj
2.) For a system classified by API RP-505, only electrical equipment is selected per NEC Article 505. Per IP15, mechanical equipment is also selected. Very few countries actually use IEC 60079 directly. Most European countries start from CENELEC EN 60079-10, which is the EU implementation of IEC 60079.From EN 60079-1, each country develops its own specific Standard (Norm).
3.) There are several significant differences both obvious and subtle. Since the laws of physics don’t change, a given facility will have similarities; but they still will not look quite the same “on paper.” Both systems, when used properly, are safe but they are still different.
Robert B. Alexander, P.E.
Answers based on 2014 NEC unless otherwise noted.