"Either..., or..." means that one of the two situations must exist, and both situations are possible. <br>"Not..., but..." means to deny the former, emphasize the latter, and emphasize a situation.
"Either ...or ..." means that there must be one situation in both cases, and there is a possibility in both cases.<br>"Not ..., but ..." means to deny the former, highlighting the latter and emphasizing a situation.
"No That is It means that one of the two situations must exist and both of them are possible.<br>"No But... " It means negating the former, focusing on the latter and emphasizing a situation.<br>