Peptides have a faster absorption rate, but you have to remember your buying X number of grams of glutamine and in reality only getting 50% of that as actual glutamine. Peptides are usually bonded with another amino acid, one is L-Glycine, cannot remember the other, I know test results show that peptide doesn’t work much better so its not worth the extra money.
Basically peptides are supposed to absorb better so their claim of it being say 3x more effective is really translated into 3 times more absorbent..But other then faster absorbtion one doesn’t rule the other, I would stick to L-glutamine it taste better anyway..