The embodiments of the present disclosure provide a method and apparatus for distinguishing between data formats, and a communication device. The method includes a terminal receives a downlink data packet, and determines whether the data format of the downlink data packet is a first data format or a second data format, wherein the first data format indicates that the downlink data packet is encrypted using a first key of a source base station and/or compressed using a first header compression format of the source base station, and the second data format indicates that the downlink data packet is encrypted using a second key of a target base station and/or compressed using a second header compression format of the target base station.