What are the differences between the Echo and having Hydaelyn's Blessing? [Spoilers?]

[treuhavik]

The Echo: Thirdly, it provides the soul armour against external interference, meaning that one cannot be tempered when one has the Echo

This should fall under the Blessing of Light. Basically, a "Blessed" is to Hydaelyn as a "Tempered" is to Ifrit - We gain protection and power in exchange for carrying out her will. Once someone is claimed by a primal (Hyd, Zodiark and possibly the Twelve included), they cannot be influenced by another.

Now, it's uncertain whether or not the echo was also provided by Hydaelyn, but it seems to me that it is rather an inherent ability, likely genetic.

But, yes, they are separate and Midgardsormr removed our "Blessing".