Excuses are "this is why I'm not at fault" and places the blame on someone or something else (including a circumstance). A reason is "this is why it happened" without trying to self-justify. A lot times reasons come across as excuses because the person has not taken responsibility for what they've done.
If a reason doesn't come with ownership of fault, it's an excuse.
Edit: see comment below about fault and responsibility
Perhaps someone can help me understand the difference between an anthropromorphic animal mascot (which as a tale as old as time) and a furry? When does one cease to be one and becomes another?
There are animal mascots all the time in sports. Why is that not weird, but it's weird to have a sporty animal mascot for coins?