Two distinct types of heroines
The eponymous heroine of Megillas Esther never sought attention for herself until she had to step up and act for the sake of her people. Esther had to conceal her identity and her distaste for the role of queen to a king who hated the Jews as much as Haman did. She had to endure living with him for years beyond her coup of saving her people, establishing a holiday, and adding a book to the canon of TaaNaCh honor that is read twice every year.
Though there is no text for it within TaNaCh, there are stories that include the heroism of Yehudith. She is the very strong and straight-forward type of heroine. She spoke up against the outrages committed against Jewish women. And she did not take a passive stance with respect to the general either. She only had to maintain a pretense with him for long enough to get him guard. Then she promptly chopped off his head with a sword. Very direct and to the point.
Another difference between the two is that of choice. Yehudith chose to act on her own volition. In contrast, Esther was taken as queen and directed by Mordechai when to keep a low profile and when to speak up. She certainly is one who had greatness thrust upon her and rose to the occasion.