The Dinaali were virtually identical to Humans in their outward appearance. However, their internal workings show several differences.
Up until the mid-24th century, the Dinaali were plagued with overpopulation, and a medical service that didn't treat the people it needed to. So the Dinaali government asked the Jye to intervene, a species known for their administrative abilities, and they reorganized the Dinaali medical system.
In the new system, each citizen received a "T.C." or Treatment coefficient, which designates how useful a person is to society.
In 2377, The Doctor was kidnapped by Gar and sold to a Dinaali medical ship. While there, he tried to "re-allocate" some medication so that the amount of medication a person received was based on how badly they needed it, not how "useful to society" they were. (VOY: "Critical Care")