Manga Envy was also vastly different from the first anime. He had two completely different alternate forms (slug-Envy and giant-ugly-monster Envy) in comparison to the first anime 'Hohenhiem's son form' and 'wierd green dragon form'. Also completely different reasons for his invidiousness. Manga: All of humanity in general--made more sense for his character, really. 1st anime: Hohenheim + Elric brothers, and that's basically it.
Their appearances and limits of their powers were different too (although apperance was only a slight adjustment). Manga Envy had far more range in terms of shapeshifting ability to his/its predeccesor....Not that it did him any good because his/its fighting ability was basically nothing in comparison to said predeccesor.