You can use both of them - but you need to calibrate them. You do this by viewing GPStracks and moving the background imagery to the correct ordination. You will find many tutorials how to do this. I order to give you more detailed information i need to know with editor you are useing. JOSM has a verry good function for calibration of background imagery.
Thank you for the reply. I mostly use ID editor but for advanced problems I switch to JOSM. If I can align them in IDeditor, I can speed up my mapping process.