According to Patricia Lines in the Humanitas Journal, Antigone and Niobe are primarily similar in terms of hubris. Much of the supporting information for this is provided by the chorus of the play Antigone.
Lines points out that Niobe's crime against the gods was that of hubris. Niobe was proud of her six sons and six daughters and boasted that having so many children made her equal to Leto, the goddess born of Apollo and Artemis. The gods were offended at the notion that any number of children could somehow compare with a god and punished Niobe by killing her children and turning her into stone.
In the play Antigone, Lines notes that Antigone feels isolated from her sister and her fiancé and she compares herself to Niobe in reference to having no one to mourn her as she prepares to die. However, this is not true because the text makes clear that Antigone's sister wished to be by her side and her fiancé is willing to confront his father to defend her. The chorus makes it clear that Antigone has pushed these friends aside in favor of being self-sufficient and, according to lines, this is the god-angering hubris that makes her Antigone similar to Niobe, though Antigone cannot see things this way.