EGR stands for Exhaust Gas Recirculation. EGR is used for controlling emissions.
A non EGR manifold does not have provisions for mounting an EGR valve or the required EGR passages to recirculate the exhaust gasses.
Everything you want to know about EGR systems:
The most common issues with EGR removal are:
1. higher emissions, possibly failing an emission test from a reading or visual inspection standpoint
2. detonation due to higher combustion temperatures
BTW.....I assume you have another RAM other than the one in your sig. It would be kinda hard to install the manifold depicted on your RAM 50!