Glutamine Peptides are far superior i've compared the two, and this is what i think. And studies show it's 3 times more effective. Glutamine peptides you can take whenever you want, the L-glutamine plain you need to take on empty stomach.
And I always take it post work out, with what ever else I may be taking, Most important is to get the glutamine back in your system. I feel it helps me recover even on gear,