Everything in 1) and 2) mean the same thing: a mistake. All three in 3) mean the same. 4) Sight and vision are also the same.

This is my take on it: 1) Botch, blunder, foul, and flub are all similar and could often be used interchangeably. * Botch is usually referring to a mistake or an error in having done something, and it often implies the person was being careless. * Blunder is also a mistake but it often implies that the error was stupid * Foul is most often used to refer to an error in sports -- it's a mistake that breaks the rules. The word can also refer to an awful smell or taste. * Flub is also a mistake. In my view it's something others have witnessed and can clearly see is an error, like dropping something, or making a mistake in repeating lines in a play. This may not be actually part of the definition though, it's just how I see that word being used. 2) Snafu is slang. It is the state of something being a complete mess, confusion, or total chaos. I never use this word :) 3) To "make a profit out of something" is to make money off of it or from it. "To make a profit on something" means you sold it for a profit, and "make a profit at something" isn't a phrase I have heard used where I live. I've heard people say, "I made a profit off it," which also means you sold it for a profit or it makes you money. 4) I believe "sight" is the actual physical act seeing things with your eyes, and "vision" is the picture in your mind or what your mind interprets from the information your eyes send to your brain.