Unfortunately vs Regrettable - What's the difference?

As an adverb unfortunately

is happening through bad luck, or because of some unfortunate event.

of an event, action, or state, allowing or deserving regret.

(en adverb)

Happening through bad luck, or because of some unfortunate event.

Unfortunately , the uproar awoke Mr. Jones, who sprang out of bed, making sure that there was a fox in the yard.

* (through bad luck) regrettably, unluckily, sadly, sad to say

* (through bad luck) fortunately, luckily

(en adjective)

Of an event, action, or state, allowing or deserving regret.

His painting his name of my car was more than regrettable , it was criminal.

It was regrettable that the teacher made the class retake the test when he was wrong about the answers.