What you can notice is the performance advantage over the Apple MacBook Air with its passively cooled processor. The more expensive MBP 13 with two fans can handle around 33 W for longer periods, so the difference is actually pretty small and not noticeable in everyday scenarios. However, we were positively surprised by our tests, because the power consumption is steady at 27-29 W after the initial spike to ~40 W, which is sufficient for 4x ~3.0 GHz. This is also the case for the Core i5-8257U in our test unit, which is advertised with a comparatively low nominal clock of 1.4 GHz. The processor also features a faster iGPU with its own eDRAM cache, but more on that later. In theory, because Apple does not limit the consumption, the cooling performance is the only limitation for the actual performance.
In theory, Apple uses 15 W processors for the less expensive MBP 13, while the MBP 13 with 4x TB3 is equipped with 28 W chips.