Either

[Sarah]

precedes two, or more, coördinate words or phrases, and isintroductory to an alternative. It is correlative to or.Either he is talking, or he is pursuing, or he is in a journey, orperadventure he sleepeth. 1 Kings xviii. 27.Few writers hesitate to use either in what is called a triplealternative; such as, We must either stay where we are, proceed, orrecede. Latham.

[Sarah]

both, indicating that each of the two following phrases must be done or will occur

[Zipporah Schumaker]

used in negative sentences instead of also or too:

[Tina]

Used before the first of two (or occasionally more) alternatives that are being specified (the other being introduced by “or”)