Based on George Bernard Shaw's 1913 Pygmalion, the movies Pygmalion, directed by Anthony Asquith and Leslie Howard in 1938, and My Fair Lady, filmed from Alan J. Lerner's 1956 play and directed by George Cukor in 1964, are two completely different movies, as are the roles of Eliza completely different. Also, the actresses portraying these parts are very different.
Wendy Hiller, the actress portraying Eliza in Pygmalion, was very convincing as the guttersnipe. She seemed to be rather rough around the edges. Her dialect was perfect when she portrayed the poor street girl. Her appearance was also perfect. One truly doubts she can ever become an aristocratic lady. I feel she never did accomplish this. She never possessed the beauty Eliza was supposed to have. Also, when she learned to speak proper English, her words continually sounded forced. After watching Pygmalion, I concluded Professor Higgins (Leslie Howard) should have lost his bet. Sure, he put her in fancy clothes and taught her to speak well, but it appeared to be completely forced.
In My Fair Lady, the infamous Audrey Hepburn played Eliza. In this movie, Eliza was not a convincing guttersnipe. Even as a beggar, she seemed too refined. In all her rags, she was still beautiful. Underneath her beggar's dialect, one can detect an educated woman. One instantly suspects she will be a beautiful and convincing aristocrat. Once she is put in beautiful clothes and taught to speak more refined, the audience suspects she has always been this way. She seems so natural. Her speech is eloquent, and her appearance is impeccable. It is so easy to forget that Professor Higgins (Rex Harrison) found her on the street. It seems that she has always been the perfect lady. In My Fair Lady, Higgins definitely won the bet. Audrey truly looked like a princess.
It seems so strange that the same character can be portrayed so differently. Directors' minds are a strange thing. I would have never picked Wendy Hiller to portray Eliza Doolittle. She just did not have it in her to pull off Eliza's rise to aristocracy. Audrey Hepburn, on the other hand, was a perfect choice. She seemed to be a princess in her own life. One can tell she can play the part of a princess superbly.