Helena is the roman/latin spelling of the name of a goddess central to ancient Greek mythodology. She's also referred to as "Helen of Troy". In Greek mythology, she was the most beautiful woman in the world, daughther to Greek god father Zeus. My sister named her daughter Helena in her love for her and Greek mythology alike.
The entry says "Latinate form of Helen." This is reasonable from an English-speaking persective, but both derive from the ancient Greek name. Helen is the Anglicized version and certainly newer. Helena is the Latin transliteration of the ancient Greek name while the English version drops the final vowel.There are two forms of the name in Greek. Modern and ancient Attic is 'ELENH and ancient Doric/Aeolian etc. is 'ELENA (the vowel shift eta-alpha was common between the dialects as in SPARTH-SPARTA). Note that the leading H is not written, but indicated by '.
My sister named her daughter Helena in her love for her and Greek mythology alike.