normally, the thermal radiation is lower in energy, than Bremsstrahlung. The planck radiation has the maximum at nearly 1 eV (our sun nearly at 2,5 eV, thermal sources perhaps 0,1 eV. Bremsstrahlung has the origin of accelerated charges. This is observed by exciting X-rays. If accelerated electrons are de-accelerated by materials, they emit photons with a short energy edge at the acceleration voltage, normally some keV. Be very carefully, if you work with Bremsstrahlung-this is dangerous for your live.
The maximum of Bremsstrahlung-intensity is observed nearly at one third of accelaration voltage (particle-energy).
Summarizing: Both sources of radiation can be distingushed by their ratio in energy - normally 3 to 4 orders of magnitude.