Maureen is the older sister and is often the more outspoken and opinionated of the two. She is also more likely to be involved in her family's affairs and to meddle in their lives. Doreen, on the other hand, is more reserved and shy, but she is also more likely to be compassionate and understanding.
Maureen and Doreen provide much of the comic relief in the series, and their interactions with Frasier and Martin are often a source of amusement. Despite their differences, the two sisters are very close and they are always there for each other.