Consider the following two sentences. 1. He must either work or starve. (either...or) 2. He must work or starve. (or) What is the difference between the two sentences?
There is not much difference. When discussing two alternative possibilities or outcomes, one of which must occur, 'either' can be omitted. If it is included, it adds emphasis.
We can use either...or to emphasise a choice. (Either…or is used to refer to two things or people.) In most cases 'either' can be omitted.
The sentences are quite similar, but there is a subtle shift in emphasis.
At the core of both statements is a logical statement: unless he works, he will starve. In the latter construction (without "either"), the statement is clear, direct, even blunt.
Using "either" takes the emphasis off the logical statement, and instead shines a spotlight on the person in question. It emphasizes choice: he is free to choose either work, or starvation. Not much of a choice, it seems … you might want to say that to emphasize choice in this context is ironic.