Words that are almost identical in spelling and meaning but are not

Some words have a huge semantic overlap that there's hardly any distinguishing them. Bucket or pail? Is there any instance where one of these is right and the other obviously wrong? (probably, but rare).

Some some pairs of words are really hard to differentiate but they have distinct meanings, if only you study the dictionary. They have considerable vague overlap, but a verifiable situations where one or the other just don't apply technically.

First in a series:

tragedy and travesty:

That poor dog dying. Was it a tragedy or a travesty? It could easily be both. A tragedy is a particularly bad outcome. Most everybody dead at the end of Hamlet (sorry, spoiler!); that's a tragedy. A travesty is a horribly distorted copy of something. The elementary school play of the Cherry Orchard had no sense of anomie; that's a travesty but not really tragic. A travesty is often tragic; a travesty of justice ended up sending the falsely accused to jail resulting in the tragic demise of his entire family. There are tragedies that aren't a travesty. Most people dying are tragic, but really that's sort of the order of things eventually. There are travesties that aren't tragic; that elementary school play. Tragedy: Hamlet. Travesty: School play