difference between different meteorological models

[JuhaszM]

I need to work with historical weather data (temperature and precipitation), we use meteoblue.com.

There (https://docs.meteoblue.com/en/meteo/data-sources/data-sources#data-sources) they write about three different types of models:

• weather reanalysis models
• weather simulation models
• satellite (observation) data

Comparing ERA5 (reanalysis) vs NEMS (simulation):

• daily mean temperature is almost the same in both models
• ERA often gives 2-4 times higher amounts for total monthly precipitation, which is just too big difference (it's for Europe, I'm interested in past 20 years)

I tried to read about the models, but couldn't find any comparison. Also don't really understand how such big differences might occur and which model shall I use.