can i comparing landsat 7 (band 6) and landsat 8 (band 10&11) thermal band? because landsat 8 only have 100m spatial resolution, so the output looks more general or blurr than landsat 7 thermal band. and what does mean TIRS band can be resampling to 30m resolution?
If you look at the spectral ranges across sensors they seem quite comparable; TM5 10.40-12.50 µm, ETM+7 10.40-12.50 µm and TM8 10.60 - 11.19 µm or 11.50 - 12.51 µm. Depending on your statistical analysis, you may have to perform some data standardization but, this is often the case with comparing multi-temporal data.
Everything collected by TM5 and ETM+7 after Feb 25 2010 are resampled to 30m, otherwise are 60m. TM8 is resampled to 30m. This is done during post processing and I believe that they use a bilinear resampling method.
To understand the differences in spectra between sensors USGS developed the Spectral Characteristics Viewer. This may help you in deciding if the sensors are comparable for your specific application.