Shavuot & Pentecost

What is the difference between shavout and Pentecost. Why is the Jewish one the 17 and Christian 23 of APRIL? They both claim 50 days.

The Jewish holiday of Shavu'ot is often translated as "Pentecost", meaning 50, because we count 50 days from the 2nd day of Passover, when God took the Jews out of slavery in Egypt 3,333 years ago, until Shavu'ot, commemorating our reception of the Torah. The Hebrew calendar date is the 6th of Sivan, and the secular date is different every year accordingly. The Christians have a different holiday with the same name, where they count 50 days from some supposed Christian event, and but it should not be confused with the the Jewish holiday with a similar translation.