The Healing Taken, Healing Received, Healing Done stats are not explained very well in game, and are a source of much confusion. I'll try to clear it up.

Healing Done is any outgoing healing. Cast a spell that heals an ally? Bonus Healing Done! Cast a spell that heals yourself? Bonus Healing Done! If you're the source of healing, Healing Done increments the heal.

Healing Taken and Healing Received actually have the same effect.
Any incoming healing is amplified by Healing Taken and Healing Received. An ally heals you? Bonus applies! You heal yourself? Bonus applies!
Generally Healing Received comes from buffs (Major/Minor Vitality), and Healing Taken is a stat found on armor or passives. But they work the same!

So why in the name of Sheogorath's well-groomed *** are there two different effects for Healing Taken and Healing Received?

Healing bonuses are *additive* with themselves, but *multiplicative* with eachother!
Example:

• Minor Mending + Major Mending = 8% Healing Done + 16% Healing Done = (0.08+0.16) = 24% Healing done
  (Any heal that comes from you is 24% stronger!)
• Minor Mending + Major Vitality = 8% Healing Done + 16% Healing Taken = 1.08 * 1.16 = 1.2528 =~= 25% Healing
  (So self-healing is 25% stronger. Better than if you only had one type of healing buff)

The effect is further compounded the more effects you stack. For example:

• Minor Mending + Minor Vitality + Major Vitality + 4% Healing Taken (from e.g. armor)
  = 1.08 * (1.08+0.16) * 1.04
  = 1.45

So you get 45% more self-healing because you stacked different effects, even though the sum of increases (8%+8%+16%+4%) would only be 36% more healing.