Yes they can sound eerily similar.
I was driving in downtown Philadelphia one day and the van in front of me suffered a "back-fire". Most of the folks on the sidewalk turned and looked at the van with the exception of the two "gang-banger" dressed individuals that were flat on the ground looking for the shooter.

They do have devices that can triangulate the source of the sound and through a computer program deliver a firing solution to the source. whether or not they can actually tell you that the sound was a gun shot is something that I don't know. Examples of the devices can be seen mounted on the humvees in Iraq and afghanistan.