Eleanor may or may not be a form of
Helen - its origin is disputed/uncertain (check the hyperlink for all of the details).
In my sister's case, in fact, Elanor is totally unrelated to
Helen or
Eleanor - my parents gave it to her in honour of the flower name in Tolkien's Lord of the Rings. In Tolkien's Elvish, 'el' means 'star' and 'anor' means 'sun' - the flower is the Sunstar, the Golden
Flower of Lothlorien.