1. Short for bits per second, bps is a measurement of the data transmission speed and indicates of how many bits pass a certain point in one second. The larger the bps rate the faster the download or upload time will be. For example, with a Modem that is 28.8bps it is only capable of transmitting a maximum of 28.8 bits per second.
2. Short for bytes per second and also sometimes abbreviated as B/s, Bps is the a speed is measured in bytes received per second. The difference between the two abbreviations is the uppercase and lowercase b.