GB and Gb- what is the difference?

For those who don't understand the difference between 2Gb and 2GB.
2GB = 2 GigaBytes ie 2048 MegaBytes(MB)
on the other hand
2 Gb = 2 GigaBits ie 256 MegaBytes(MB) [ 2048/8 = 256 ]

as 1 Byte = 8 bits