There are no difference between keyboard mode and the input method mode. Some keyboard mode will invoke the input method function and some will not. There are four keyboard modes:
This is to input the Alphanumeric characters. The Alphanumeric mode is exclusive with the Tsangjye mode and Phonetic mode.
This mode invokes the Chinese Tsangjye input method, and the user can type in the Tsangjye defines radical character (normal and well known Chinese characters). The combination of these radical characters compose a Chinese character. If the combination is valid to compose a Chinese character, the result Chinese character is sent, else the error message is shown. This input method is most popular among skilled users.
This mode invokes the Chinese Phonetic input method, and the user can type in the Phonetic symbol character (Most Chinese students learned them in primary schools). The combination of these characters is mapped a candidate list of Chinese character. The user selects the candidate from the candidate list and fix it by the enter key.
These modes have effect on only Alphanumeric characters.