1 TB has 10 raised by power of 12 bytes ( 1,000,000,000,000 bytes).
1 TiB has 2 raised by power of 40 bytes ( 1,099,511,627,776 bytes).
So when you see Tib Notation you will see about 9% lesser capacity compared to TB. TiB makes more sence since the data on the tape ( or hard drive) will be stored in Binary format. Why not represent the storage cpacity in Binary base.