If you want the dictionary definition, just double click on any word.

Councillor  is a noun which means an elected member of a local government.

For example: "He was elected to be a councillor in 1998."

Counsellor is a noun, which means someone who is trained to listen to people and give them advice about their problems.

For example: "The student union now employs a counsellor to help students with both personal and work-related problems."

Thanks to Daniel Hugo