According to Seagate's website, the ES series is for Server & Enterprise Storage. Here's a page
on Seagate's website that may shed more light on this.
Here's another page for the 7200.11 series
, which is for Desktop Storage.
If it's meant for Server & Enterprise, then you know it's going to be better and more reliable in comparison to consumer hdd's such as the 7200.11. This isn't to say that their consumer hdd's aren't reliable. It is my personal opinion that they are the best consumer hdd's on the market.