Data rate and data transfer rate can refer to several related and overlapping concepts in communications networks:

Achieved rate

• Bit rate, the number of bits that are conveyed or processed per unit of time
  • Data signaling rate or gross bit rate, a bit rate that includes protocol overhead
• Symbol rate or baud rate, the number of symbol changes, waveform changes, or signaling events across the transmission medium per unit of time
• Data-rate units, measures of the bit rate or baud rate of a link
• Data transfer rate (disk drive), a data rate specific to disk drive operations
• Throughput, the rate of successful message delivery, or level of bandwidth consumption

Capacity

• Bandwidth (computing), the maximum rate of data transfer across a given path
• Channel capacity, an information-theoretic upper bound on the rate at which data can be reliably transmitted, given noise on a channel