betwixt and between
meaning: between two positions, choices, or ideas; not really one thing or the other
example: A lot of us feel betwixt and between our roots and our branches. — Casey Cep, The New Yorker, 28 Mar. 2022
The two words are of the same meaning
Perhaps you've always said "between the two of them" That's fine. Betwixt and between have similar origins: they both come from a combination of be- and related Old English roots. Both words appeared before the 12th century, but use of betwixt dropped off considerably toward the end of the 1600s. It survived in the phrase "betwixt and between" ("neither one thing nor the other"), which took on a life of its own in the 18th century. Nowadays, betwixt is uncommon, but it isn't archaic; it's simply used more consciously than between.
