Difference between Bytes and Bits in computer-speak?

Bits: Data in motion

Bytes: Data at rest

There are 8 bits in 1 byte. If you assume that they are the same thing, you are off by 8x

Suppose you have a 80Mbps (megabits per second) download connection from Comcast. In order to calculate download time on a 20MB document, you have to do a little bit of math.

Advertised Bit Speed: 80Mbps
Byte Speed: 10MB/second

Time to download: 2 seconds

Since you have 8 bits per second, you need to divide Bit Speed by 8:

80Mbps/8

which yields 10MB/second