Both angels and devils are remote controled devices of The Lord. The only difference I can see is that we think they have a different antennas:
Devil - "Rabbit ears" dipole antenna
When The Lord wants to tell us a good news, sends an angel. When wants to tell sad news, sends a devil. When wants to guard us, sends an angel. When wants to penalise us for some bad behaviour, sends a devil.
Summarising all known information about these two characters, I came to these strange results. Sorry, my enginner's mind can see a logic sequence here... What is the moral? We are responsible for every one step/thought we do/think. And The Lord always sends us "feedback", we must just listen and follow...
But we are in comfort to think, that process works backward - first a devil tells us some mischief, and then we do it after him. Easer to skip responsibility. Actually, doing what the devil say, we "consume" the penalise. And also we think, that this is something good/fun/satisfaction for us. When an angel guards us, we again think this is good/fun/satisfaction for us. Yes, angel gides us to different results, than devil, but all this is just result (echo) of our past activity...
And finaly, is there difference in the mail/messanger, which can depend of "holded info"?
Am I right in these toughts?