In computer lingo, the lower-case “b” refers to “bit” and the upper-case “B” refers to “byte.” Both are units of data, with 8 bits equal to 1 byte. 1 megabit denotes 1,000,000 bits, and 1 megabyte denotes 1,000,000 bytes. Mbps stands for Megabits per second. MBps stands Megabytes per second.