There is a difference because these are two different models of the game. We aren’t using simulation, we are using a formula-based model.
For a difference this small, it is unfortunately not really possible to verify for sure which model is better. This is because it is impossible to set up an in-game test that could measure this for us and get enough controlled trials to overcome statistical error.
Since there is no way you’d ever be able to tell which of these setups is “better” just by playing the game… Our position is that you are safe using either model to pick your gear.
We use a formula-based model because it gives us a lot more flexibility than a simulation model. It can calculate solutions way faster, which then allows us to add more options to the website to let people adjust the gear advice to their preferences. We also build the models to smooth out noise and jumpiness in the results that are artificial and due to the model itself.
Simulation is not good for comparing one setup to another. Simulation is good for generating large data sets and then aggregating the results to find statistical trends. This is because there is a lot of “noise” in simulation data, and we have no way to measure the structural error inherent in the model. We have been arguing for years that the way the community uses simulation to compare one set of gear to another is an inappropriate (mathematically) use of simulation.