Some confusion here

Sometimes you end up visiting strange sites. This is a question & answer site. The question is:

Obviously, this is not a good question. It is something like "what is the difference between a ham sandwich and butter?".

The answers are not so good either. 

"Simple X"? Spelled like this, one would suspect that any method is more advanced. However, big-M is not a replacement for the Simplex method. It is just a simple modeling trick to handle models with an infeasible starting basis. Big-M methods are not used in practice. (Note that there is also a big-M concept in integer programming. There it is used to model implications with binary variables.)

Here is the "expert-verified answer." Basically, the same answer. "Big m" is usually spelled big-M (the M is big).

When I paste the question into ChatGPT, I get a better answer: https://chat.openai.com/share/f4baca78-f1d7-476f-8cf5-a5ad278ff036. Not perfect by any means. E.g. the sentence:

While the Big M method is a viable approach, the simplex method is typically preferred due to its efficiency and robustness.

is not correct. This sentence is about the Simplex Method + Big-M vs the Simplex Method + two-phase approach.