Assuming I understood correctly, we are talking about comparing a measurement by tag “Stue” to a measurement by tag “Test” at the same time.
If so, when comparing one sensor to another sensor, it’s the absolute accuracy that matters. Basically, the absolute accuracy means the accuracy when observing the absolute value, for example “the current atmospheric pressure is 1025 hPa”. Relative accuracy means the accuracy when observing the relative pressure differences experienced by one individual, for example “the pressure is now 2.5 hPa more than what this sensor measured two minutes ago”, without taking into account what the absolute value is or was.
Basically the absolute value (where the absolute accuracy matters) is the measured absolute value at a given point in time, the relative value is when you compare one measurement at a given point in time to another measurement at another point in time by the same individual sensor.
For a practical example, imagine an old style analog thermometer with the thin glass tube filled with a colored liquid with lines and numbers painted next to it, it’s easy to cause a relatively large error margin in the absolute measurement if you poke the glass tube up or down, causing the apparent height of the liquid change place (along with the entire glass tube), but even then, the relative accuracy is not affected by it, because you can still see that the apparent measurement has increased, say, two degrees since one hour ago, irrelevant from whether it changed from +6 to +8 or +11 to +13. And thus, when you compare this one thermometer to another individual unit, the absolute (in)accuracy of both units make a difference, because you are comparing the absolute value of both units.