ЖЕ vs И
И and же can both add emphasis, but the kind of emphasis is different.
И usually emphasizes that something is exactly the expected, logical, or relevant result. It often has the meaning "indeed", "actually", "exactly", "and that is what happened."
Он и пришёл. - He did come / And he actually came.
Я так и думал. - That's exactly what I thought.
Он это и сказал. - That's exactly what he said.
Я этого и хотел. - That's exactly what I wanted.
Here и focuses on the element that completes or confirms an expectation:
Я хотел поговорить с ним. Я ему это и сказал.
I wanted to talk to him. And that's exactly what I told him.
Же works differently. It usually points back to something that should already be obvious, known, remembered, or accepted. It can express insistence, contrast, impatience, correction, or "after all / you know / indeed."
Я же сказал тебе! - I told you! / I did tell you!
Он же врач. - But he's a doctor! / He's a doctor, after all.
Это же невозможно! - But that's impossible! / That's obviously impossible!
Ты же знаешь. - You know that.
Compare:
Я это и сказал.
That's exactly what I said.
Я же это сказал.
But I told you that! / I did tell you that!
The first sentence with и identifies what was said: "that is exactly what I said."
The second with же reminds the listener of something they should already know: "I already told you that."
Another comparison:
Он и пришёл.
He actually did come / He came, just as expected.
Он же пришёл.
But he came! / He did come, remember?
So they are not interchangeable.
A useful rough distinction is:
и = "exactly that / indeed that / that is what actually happened"
же = "but / after all / as you know / I am reminding or insisting"
Also, emphatic и often works as part of common constructions such as:
так и... : Я так и знал. - I knew it.
вот и... : Вот и всё. - That's it.
именно ... и... : Именно это я и хотел сказать. - That's exactly what I wanted to say.
Же is much more connected with the speaker's
