Any learner of Greek or Russian will tell you that learning a new alphabet is no great task. However, there are certain false friends to look out for – for example, Greek’s letter rho (Ρ), looks exactly like the Latin letter P, but is pronounced like an “R” rather than a P. Similarly, the Cyrillic letter У looks like a Latin Y, but in Russian is pronounced “oo”.
While the actual pronunciation or exactly what each letter represents in each language can differ, there are 11 letters that exist in all three alphabets. This Venn diagram shows the common letters – the Greek alphabet is on the left, Latin on the right, and Cyrillic on the bottom (note that only capital letters are shown).
The Latin and Cyrillic alphabets all stemmed from the Greek alphabet, so it is not wholly surprising that there are still common forms, despite the fact that plenty of new letters and variations have appeared in the last 2500 years.