Saving Throws Question

[ElCadaver]

Is there any benefit in getting Bonus to Mind Effecting Spell saves over just bonuses to Will Saves?

For example

+2 Mind Effecting Spell saves on an item of armor costs 2000gp

+2 Will Saves saves on an item of armor costs 1000gp

I can't find out what the difference is.

Anyone?

[Zelknolf]

Not all mind-affecting saves are will saves (for example: Weird, Phantasmal Killer) and not all will saves are mind-affecting (for example: Inflict Serious Wounds).