The difference is that one is very granular and done in reaction to a crime. The other is a wide scale collection of data which is necessary recorded.
The problem is mass data collection without suspicion, probable cause, or warrants whatsoever. That's a brand new thing, other than the places in the world unfortunate enough to have roving gangs of police going door to door and searching homes without warrants. This facilitates it on a scale that's never really been seen before in human history.
Everybody who talks about cryptography is arguing about that! With the digital technology we have, the options are very simple: either every man in the middle can read (even the villain), or nobody can (not even the justice departments). There's no middle ground.