Translators are low powered FM stations operated for the purpose of re-transmitting an existing AM or FM radio station without significantly changing its content. A complex set of rules govern translator service, including that translators are considered a secondary service and can be forced to change frequencies or leave the air altogether if in the way of a full-service station wishing to upgrade or relocate its transmitting facilities.
For more information about Translators: https://www.fcc.gov/media/radio/fm-translators-and-boosters#TRANS
Boosters are used to re-transmit an FM radio station in order to overcome limitations of terrain or other factors within the FM station’s authorized coverage area.
For more information about Boosters: https://www.fcc.gov/media/radio/fm-translators-and-boosters#BOOST