What's in a word?

Despite being an enormously popular and global language, English is full of difficulties. Setting aside the obviously frustrating examples of ought, bough, cough, dough, slough or similar spelling conundrums (conundra?), there are also words that seem synonymous but are not. For example: wistfulness vs. regret.

Wistfulness feels like longing, or wishing, while regret feels like something you can't take back. The wistful person is saying to themself, how wonderful it would be if only this could happen, while the regretful person is saying, this happened, and now I can never make it better. Wistfulness could be flowers, could be something colourful off to the side, just in the peripheral vision for a quick second. Regret is a black hole, a dark room. Regret is more relentless. It pulls you down.
     Another example–one we use to assess higher thinking processes in people having memory impairment–is lie vs. mistake. The easy answer is, a lie is untruthful on purpose, while a mistake is an "accident." Not always true, of course; sometimes a mistake is more carefully crafted than we let on. Oh sorry, I didn't mean to do that...but on some level we did. Maybe not a conscious level, perhaps we double-booked ourselves despite a nagging feeling there was something else going on, and didn't bother to check. A lie, or a mistake?
     A lie is a dagger, an arrow; deliberate, precise, potentially hurtful. A mistake is a random stone, flung into the air and hitting someone on the head. There are gradations in the mistake. You may have had your eyes closed, or you might have been aiming just the slightest bit. You may have known that the likelihood your stone would hit someone was not zero, and you threw it anyway. Similarly, a lie can sometimes be considered good: sparing someone's feelings seems like a useful reason to lie, but remember the arrow. It's still potentially hurtful.
     Words like these, fuzzy distinctions like these, make me glad that English was the first language I learned, one that I continue to explore all the time.