I can see your astonishment: "What a silly question! There is no difference."
I kind of agree. One definitely can't tell any difference, from the data itself. In this sense, they are indeed the same. But are they really? Well, one is the original and the other its copy, of course! "What a silly answer! ", you might exclaim. Maybe it is not as silly as it looks. Ask yourself the following two questions:
If the original data changes, is it still the original? The answer is surely "Yes". Because it’s the original, it can do whatever it wants and still remain the original.
If the copy changes, is it still a copy? The answer is clearly "No". Because of the change, it no longer is a copy of the original.
Here is some difference, isn’t it? But if we can't find any difference in the data itself, where does the difference lie? Intuitively, it seems that somehow the difference lies in the "derivative" of the data, evident only when changes happen. Bingo! The "derivative" of data is really its meta-data. So, the difference between data and its exact copy lies in their respective meta-data, here in particular their originations: the original data was created from the original data generating process, while the copy from making a copy of the original data.
"So, you got me. What's the big deal?", now you say. Well, this inability to tell the difference between data and its copy in our systems inevitably leads to "possession = ownership" being true in our systems, which happens to be the very root cause for all our cyber security problems and also the reason why no system has genuine intelligence yet. Sounds like a big deal to me, stay tuned…