"What are the differences between Format and Initialize in hard drives?"The answer depends somewhat on the software being used to do the two functions. In general you can think of format as a lower level format and initialize as a high level format. A high level format basically clears the drive by zeroing the data that keeps track of where all the data is on the drive. The data is still there (until you write over it), but since the drive's table of contents shows nothing is there it behaves like a blank drive. A low-level format actually goes in and zeros each block of data on the entire drive (which can take a while on larger drives). The drive will also remap any bad blocks it finds. Sometimes a low-level format also includes setting up parameters such as the size of the cache and so forth.