Here is the list of EX certifications, depending on the country where the machine will operate, as some certifications maybe required or not:
ATEX : mandatory for Europe
CCC : mandatory for China
Kosha : mandatory for Korea
UL : could be required for North America
IECEx : international standard, well recognized
Note that some other countries could have also their own local certification body.
Motor construction and marking could be different according to the certification required.
(ie : a UL674 motor is not compliant to IECEx standard and vice versa)
For EY motors (Zone 2), it is only certified ATEX (Europe)