DIFFERENCE BETWEEN TOO AND NEITHER/EITHER :

like pizza, and my wife does too.

I don’t like carrots, and my husband doesn’t either.

A: I’ve been to Korea many times.

B: Oh really? I have too. What’s your favorite place in Korea?

A: I’ve never been to South America.

B: I haven’t either, but I’d really like to go there one day.

A: I can play the piano.

B: Oh really? Me too!

A: I can’t cook very well.

B: Me neither.

There is no difference in meaning between “either” and “neither”. We use “either” when there is another negative word in the sentence such as “not” or “never”. For example:

A: I’ve never tried scuba diving.

B: Oh yeah? I haven’t either.

However, we use “neither” when there is no other negative word in the sentence. For example:

A: I’ve never tried scuba diving.

B: Oh yeah? Neither have I.

So, we can say “Neither have I.” or “I haven’t either.” but we CANNOT say: “I haven’t neither.” because there are two negative words in the sentence.