Ultrastar DC HC560, 20TB vs Ultrastar DC HC570, 22TB

What are the main diferences between Ultrastar HC560 (20TB) and HC570 (22TB)?
Of course, beside price and capacity.
Is there any technical improvement?
I want to buy one of these two, as soon as possible.
Thanks you.
DANIEL (Romania)

They seem to be similar. Same performance, same areal density. The only real difference seems to be the number of heads, 20 versus 18.

Hi and thanks for the reply!
What is number of heads? Wich one is better? Less or more?
Thank you again.
DANIEL (Romania)

Less heads means less things to go wrong.

A head is the part that flies over the surface of the platter and performs the actual reading and writing.

HDD from inside: Hard Drive Main parts:

The Law of Averages will laugh at that, and prove you wrong.

I’ve had 1TB drives fail at the same rate 4TB drives.