difference between bw freq band

These are basic names of how communication systems operate.

Center frequency means that the frequency band or range has a width around the center value.

Communication traffic is organized in channels which do not overlap, and their channel bandwidth is adjusted according to the type of modulation and data rate.

IF frequency or intermediate is used in superheterodyne systems. The higher (or lower) frequency of RF or microwave transmission (e.g. through space) is converted to the lower IF frequency where it is easier to process the signal, by amplification, filtering, and demodulation.

Find a textbook on radio communication, there are more detailed explanations.