Motor winding is slighly thicker in 500W hence difference in weight 3.9kg vs 3.6kg Everything else is the same including controller and software.
They are totally different motors, in as far as smaller or lager windings etc. So the nominal power rating denotes the motors physical construction and is not a simple matter of different firmware.
To state the obvious they are new so not tested over time. I've had the DM02 since September last year and done over 1000kms on it. Power wise, think the performance of a Bosch Performance Line CX or Shimano Steps e8000. It is superior to a Giant/Yamaha Core. ToSeven are continually refining their firmware so the 'motor' I ride now is leaps and bounds better than the 'motor' I bought. There is propriety flashing cables, which are now bought seperately, and firmware up dates are posted on the ToSeven website. I've had teething problems to be sure but the go-to space for info on the ToSeven motors is the High Voltage Electric Light Vehicle discord page.
I would not say totally different motors. Main difference is a winding. The same story with DM01 750W vs 1000W. Mechanically the same but with less dense winding.
