The Greek language uses a different alphabet than the one used by most Western languages, which derives from the Latin alphabet. Thus, all Greek words presented in languages other than Greek have to be transliterated (transferred from the Greek alphabet into the Latin one). Furthermore, as discussed in chapter 3 of this book, for a long time the Greek language was "lost" to people in the European West, and most Greek literature, history, and philosophy were only known through Latin translations. As a result, there was a common tendency to present Greek names and words first in their Latin translations (Venus for Aphrodite, for example) and then, when using Greek words themselves, in a Latinized form.
In the past few decades, there has been a growing trend among Hellenists (people who study ancient Greece) to use transliterations closer to the original Greek spellings. Technically speaking, the most common differences between the Latinized versions and the Greek versions are with the letters k and c, and the endings - os and - us. The letter c did not and does not exist in Greek; they have the letter kappa (k) for the k-sound, and sigma (n) for the s-sound. When the letter c appears in Greek words, it is usually a Latinized replacement for a kappa, thus Socrates (Latinized) versus Sokrates (Greek). The same goes for the Greek letter khi (x), which is transliterated as ch in Latinized forms, kh in Greek. Likewise, the standard masculine word ending - us is actually Latin, being the equivalent of the Greek - os, thus the difference between Mt. Olympus and Mt. Olympos.
The problem now with transliterations from Greek is how Greek to keep the words, a decision that is generally up to each individual author. Quite frankly, it is difficult to go 100 percent in either direction. Some Latinized forms now look quite out-of-date, such as Cnossus for the city of Knossos. For other words, though, the Greek form looks completely alien, such as Epikouros for Epicurus.
I originally wanted to keep the transliterations in the book as Greek as possible. However, I polled a group of my students, who overwhelmingly preferred the "normal" (Latinized) spellings. And so, with a few very minor exceptions, such as Olympos for Olympus, the more common, Latinized spellings have been used.
One final note on pronunciation. There is no silent e in Greek. E is a common word ending in Greek, and in this book I frequently wrote it as e to emphasize its pronunciation. This was mainly so for words that might not be as familiar to the reader, such as Persephone (per-SEF-o-nee) and the city of Priene (pre-EN-ee).