It depends on many other factors too, like hardware combination used in it (Soc, Display size and type, RAM, other sensors etc), software optimisations, smart features, bloatware, operating conditions, and usage patterns and a lot more.
Galaxy S4, Galaxy S6 (2550mah, but power efficient), Galaxy Grand prime and Galaxy J5 have same battery capacity 2600mah.
But the battery timings are not exactly the same, because of different hardware and software.