Comment by masklinn

>Data bit rate = the rate at which the data bits provided by the user are sent

> Signaling bit rate = the rate at which bits are sent over the physical communication medium

There is a third one: in addition to the line coding, there's the message framing (at the logical level) e.g. USB 3 has a signalling rate of 5Gb/s, it has a raw data rate of 4Gb/s, but it has a theoretical effective data rate of around 3.2Gb/s (400MB/s).