I think they are exactly the same, the only difference being regional usage.

“Excuse me” can be used for the following circumstances: if you are trying to pass through in the middle of two people, if you are asking someone to be excused or removed from a situation, or if you are asking someone to repeat what they had just said. “Pardon me” is not widely used in American English, but you would see it in any other English dialect all over the world, and basically just means, the speaker is asking to repeat what was just said. 

excuse me is far more common. pardon me feels very old fashioned or formal.

We make excuse, for an apparent fault, or, slight offence: we ask pardon, for a real fault, or, when the offence is greater