As petersonra said, for a Div 2 location, both can be used. So both can be treated the same in this situation.
They are not quite identical. For example, "non-incendive" allows currents up to the ignition limit of the atmosphere; "intrinsically safe" only allows current up to 2/3 of the ignition limit.
The reason is that non-incendive is only OK for Div 2 locations, where gas is not routinely present, and so lower risk. Intrinsically safe is allowed in Div 1 areas where gas is continually present, which is a much higher degree of risk. Hence, a safety factor is applied in Div 1 situations.
They both do limit the available energy to prevent ignition, which is why the wiring methods are similar.