Spot the difference ...

One of these cases is not like the other, one of these cases is not quite the same. Can you tell why?

So the police investigate a complaint by the Prime Minister against a member of the media, where it is alleged that a "private communication" was intentionally intercepted using a covert recording device. Even though Assistant Police Commissioner Malcolm Burgess labelled Bradley Ambrose's action as clearly illegal, the decision not to take him to court is explained on the basis that "a prosecution was not required in this instance."

However, in the next breath he effectively admitted there actually wasn't sufficient evidence to convict Mr Ambrose of any offence as: "In the view of police investigators, the recording was "most likely" on purpose, but at the least "reckless"."

Then the Police investigate a referral by the Electoral Commission against Radio Live, where it is alleged that the provision of an hour of radio time to the Prime Minister a few weeks prior to the election is in breach of the Broadcast Act. The decision not to prosecute is explained on the basis that: "We have determined that there is insufficient evidence to satisfy the requirements for prosecution."

This is despite the Electoral Commission concluding that the relevant programme was an "election programme", and thus broadcasting it is unlawful. 

Thus in one case, uncertainty about the evidence leads to a simple "we're not certain enough there would be a conviction to warrant pursuing the matter" message. On the other, uncertainty about the evidence is glossed over in order to deliver a stern "you broke the law and we'll ping you if you do it again" message.
And the reason for the different approaches is ... ?