Hello!
The difference between <em>tone</em> and <em>mood </em>is:

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Tone:
Tone is what the <em>author </em>feels about what s/he is writing. It reflects the writer's feelings.
Mood:
Mood is what the <em>reader </em>feels about what s/he is reading. It is intended to shape the reader's emotional response to the literary work.
<em>Sometimes </em>the mood and tone can be the same. This isn't always the case, though.
When a word contains a feeling it’s usually because the word sounds related to an emotion.
can you put more info about the subject?
The Situational Irony that occurred in "The Colomber" by Dino Buzzati was the fact that Stefano gave up his dream of becoming a sea captain to ensure that he will live a long life after seeing the Colomber.
It was believed that the Colomber was a harbinger of Death and that whoever sees it will be doomed for life.
However, the reason why the Colomber was after Stefano was because it was tasked to give Stefano a pearl that will give him good luck and success in life.
It is ironic because the reason Stefano feared the Colomber was false and baseless.