Shabbos (stress on first syllable, second vowel “o,” ends in “s”) or shabbat (stress on last syllable, second vowel “a,” ends in “t”)? Why can’t we agree on how to pronounce Hebrew?
How about beth, bet, or beis? Shibboleth or sibboleth?
When I was 14, the age when one knows everything, it was simple. Rabbi Hecht taught me that there are two ways to pronounce Hebrew: the Ashkenazi pronunciation (shabbos) was in his view correct, even though modern Israelis prefer the Sephardic pronunciation (shabbat).
He was more right than wrong—close enough for a 14-year-old, even one already interested in linguistics—but not completely right. Of course he had the orthodox point of view, since the hospital of which my dad was Superintendent and Medical Director pretty much had to hire an orthodox rabbi as its first Jewish chaplain, on the (probably correct) theory that non-orthodox Jewish patients would still accept an orthodox rabbi but not vice versa. We’re talking 1961, which of course was culturally still the ’50s, so no one ever brought up the idea that there should be more than just three chaplains: one Catholic, one Protestant, one Jewish.
Today I most often hear the distinction expressed differently: as Hebrew vs. Yiddish rather than as Sephardic vs. Ashkenazic. But that isn’t quite right either; it’s just a partial error in the opposite direction. Yes, Yiddish uses Ashkenazic pronunciations, but the truth, of course, is more complicated than that. You can find one (partial) summary on Quora:
So there we have something closer to the truth, in that it explicitly points out that we have here a difference in dialects (more than just two!), which should be the central point. But how does Yiddish fit in, and what’s up with that final consonant? You really need to read an article titled Pronunciations of Hebrew, which gives you the full story. Warning: some of the comments by readers are well-informed, some aren’t! I suppose that’s typical, but you still deserve to be warned.