Question:
What is the difference between GB and GiB information units?
Answer:
There are actually two differences.
The first of these, as noted in the accepted answer, is that the terms "kilobyte", "megabyte" and "gigabyte" according to the IEC recommendation should mean 1000, 1,000,000 and 1,000,000,000 bytes, respectively. In contrast, the terms "kibibyte", "mebibyte" and "gibibyte" should mean 1024, 1024² = 1,048,576, and 1024³ = 1,073,741,824 bytes.
In reality (and this is the second difference), “bi” options are practically not used, and in everyday communication, kilobytes, megabytes and gigabytes most often (but not always) mean exactly 1024, 1024² and 1024³ bytes. This creates confusion, but terms like "kibibyte" are so dissonant that you have to live with this confusion.
However, manufacturers of disk drives and RAM chips often use traditional units ("gigabytes") to refer to the capacity of their devices, using them in the sense of the IEC recommendation (that is, they have 1 GB = 1,000,000,000 bytes). Critics argue that this is done less to support standardization than for marketing reasons.