tompoland - Most machines have a programable offset parameter which aims to display the right temperature at the group based on the actual temperature at the boiler. For instance, the difference between temperature inside the boiler and the group for the Lelit Elizabeth is 10C. Therefore, a temperature of the water measured inside the boiler of 105C translates to approx. 95C at the group. On my Profitec 700 I used to have (E61, dual boiler), if memory doesn’t fail me, the offset was around 14C.
Different machines would have different architectures and constructions, so it’s all relative. With the ACS V Evo Leva, you can actually set the actual temperature at the group, as it has dedicated heating cartridges and monitoring at the group itself, so you can fine tune that really well.