Title pretty much sums it up. Did they view each other as heretics or did they accept each other since they're pretty much the same religion with different names?
See these threads for why the Greek and Roman religions were not just the same thing with different names:
How did Roman religion differ from Greek? by /u/skreczok
Apart from the name differences, were there other changes that made the Roman gods different from the Greek Gods? by /u/artfulorpheus