difference between series 1 and series 2 rb25det ecu ?

[dethatch]

I have a series 2 engine and possibly a series 1 ecu..how can you tell..I have heard the s1 has a light on it. and s2 does not. also heard you can run either on either engine...just want to make sure..I want the engine to run on its factory ecu before I plug in the power fc as to not cook the power fc in case something is wrong. much rather have all the bugs worjed out using the stock ecu before I do anything else

[as240]

my series 2 ecu has a light on it as well.