A recent tweet by the Overwatch official twitter confirmed that Blizzard’s popular new IP will be balanced separately on consoles and PC.
This confirms the comments made by game director Jeff Kaplan about the sensitive nature of patching the game. He addressed concerns where they didn't want to harm the console experience with PC specific changes. Nor did they want to lessen the PC gaming experience with console exclusive changes. -- He also went on to state that the difference in balance would only differ from PC and consoles and not PlayStation and Xbox.
Having separate balance changes for each platform ensures that the player-base for both PC and consoles retain a polished experience. Considering that different control schemes warrant different balances, this will keep heroes in the game from being unnecessarily buffed or nerfed on either platform.
For an example on hero difference between platforms, we can take a look at Tracer. On PC; Tracer can be targeted fairly easily and taken down due to a more precise targeting input. On console however Tracer’s blinking and movement speed make her a harder target to shoot.
With recent talks about other changes, it will be interesting to see what platform specific changes are made to heroes as Overwatch evolves.