Looking at your numbers - the 15-inch started with a higher capacity battery. The 13-inch is 75% of the 15-inch to begin.
So, percentage of capacity compared to original capacity on both would be 88% and 92%, respectively.
From that angle, the 15-inch is just under 90%, and the 13-inch is still slightly above 90%.
Apple should replace your battery if you are covered by AppleCare, and the battery health drops below 80%, with less than 1,000 charge cycles.
You currently are not close to the 80% level.
However, if you can convince Apple to replace your battery when not justified, then a new battery would be nice, just not necessary at this point.
I think it is difficult to compare two laptops, when the usage (apps that you usually are using, and your particular setup on each can be significantly different, even if they appear to have to same apps).
I think the only way that you can compare battery use between two laptops, would be if you typically plug into adapters, and disconnect adapters at virtually the same time, each time, then use each in an identical manner, for approximately the same amount of time, launching and quitting the same apps at roughly the same time.
The two MBPros will never be the same.
Kinda like comparing apples and oranges (sorry!

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