Answer and Explanation:
Abigail was kind to the Proctors when she worked for them. This kindness was exhibited by Abigail because of the love affair she had with John Proctor and as she did not want his wife to suspect, he was kind to her too. Since this case was misrepresented and she was fired from the Proctors' house, she changed from kindness to jealousy and bitterness, especially towards Elisabeth Proctor, even going so far as to lie accusing her of being a witch. Abigail was also extremely manipulative, accusing everyone who was against her of witchcraft.
Mary Warren, on the other hand, was weak and prone to hysteria when she replaced Abigail at the Proctors' house. She was a person who did not want to get into problems and discussions because she did not have the spirit strong enough for that. However, when she saw Elisabeth being wrongly accused, she decided to gather all the courage she had to help her, but was soon influenced by Abigail not to help anyone and to accuse John of witchcraft. That's what she did.