Ἑλένη and Ἑρμιόνη. As far as I know this 'inverted comma letter' in the beginning is always H in LATIN(IZED) tradition. In Russian it can be either "Г" (old Greek transliteration system used to sound as in Ancient Greek for classical names as Геракл, Гераклит, Геродот и т.п., LATIN tradition also uses it) or 'no sound at all' (new system, close to new Greek tradition, and used in Russian for contemporary names).
So in Russian, as Елена is a contemporary name (and a popular one), it falls into the second category ('no sound at all').
Other classic examples would be: Hellenistic vs Эллинистический, Helio- vs Гелио- (all things related to sun). You always have H in English, but in Russian 2 cases are possible.
The historic development of Greek and changes in Greek pronunciation resulted in such intricacies.