Why is cooking a food item method called different things by what the item is, or what is the criteria?
On the Food network they boil potatoes, but they poach carrots.
They poach turkey, but they boil eggs.
They sauté' onions, but they fry eggs in the same pan.
Likewise, they fry hash browns, but they sauté' onions in the same pan before adding the potatoes.
It usually has to do with what chemical process happens to the food in question. Not all foods react the same to being dunked in boiling water. (Although I couldn't tell you what the difference between potatoes in boiling water and carrots in boiling water.) In the case of onions vs eggs, the same process is 1) extracting the water and using it to make sauce, with the onions, or 2) boiling off a tiny amount of liquid and heating the proteins to solidify them, in the case of eggs. Same method, wildly different chemistry.
Sometimes it has to do with how long that cooking method is applied, since a different thing happens. For example, you can poach OR hard-boil an egg; same method, different amount of cooking time.
In short, with a few exceptions, it's not about what process you're applying to cook the food, but about the result that it achieves in the food item.
Poached and hard boiled eggs vary by more than just their cook time. These names are much less about chemical processes and more about differences in technique. See other comments in this thread.
If I hand you an egg and tell you it's a poached egg, you're going to thinking about the consistency of the egg, not how I cooked it. Poached means the result, not the process.
If you hand me a poached egg, I'm not going to take it because I can see it has no shell and it's going to be all over me staining me with the runny yolk. Now if you gave me an egg with a shell and told me it was a soft-boiled egg, I would think about the consistency.
I mean... you get the result by doing the process. You can get different consistencies based on how long you cook them for.
They're different techniques with different results. You can't give me a boiled egg and say it was poached and have me not be able to tell. Nor vice-versa. You can have runny boiled eggs, you can have soft-boiled eggs, you can have hard-boiled eggs, but you can't make a boiled egg look like a poached egg.
This is a thread about why they use certain words, though. It isn't a thread about how to cook an egg. They use the word "poached" to mean a certain consistency. To poach an egg means to produce an egg with that consistency. In fact, as far as the recipe is concerned, it doesn't matter whether you heated up any water at all: if the instruction is "poach an egg" and you inject a Maxwell's demon to heat up the individual molecules of the egg the appropriate amount, the result is a poached egg and that's still what you call it.
They use words to mean what the result is.
More to the point, the reason they use language this way is that many results in cooking can be achieved through multiple different processes. Chefs come up with different solutions to the same problem. Talking about how the solutions work is interesting, but it gets in the way if you're talking about a basic step in the middle of a recipe. If you know multiple ways to get to that result, and you don't want to prescribe any particular one, you use a word like "poach" or "fry" and assume that the cook following your recipe already knows at least one way to get there.
I didn't reply to the thread, I replied to you. You said the difference between boiled and poached egg is the consistency, which is not true. The difference between poached and boiled is the process. If you poach an egg for 1 minute vs 5 minutes, you'll get wildly different consistencies. They'll both still be poached eggs, however