Enfamil gentease neuropro vs enfamil gentlease regular?

Lo

Currently my twins (2months old) are on gentlease neuropro. Last night my husband brought the gentlease regular (he got confused...) and i was wondering if there a difference between those two? I dont want to messed up with their system by giving a different formula. Can sombody tell me if there is any big difference and which one is best?