A smiley face is simple and plain, but a Happy face is knowing and sure.
Happy knows that all is well, troubles can be overcome, challenges accepted and contentment comes from within.
The Mood Wheel
The Primary Moods (Basic Moods):
Glad (Yellow) - joy, mirth, exuberance - Acceptance of Pleasure
Mad (Red) - anger, fury, wrath - Conflict with Pain
Sad (Blue) - sorrow, melancholy, grief - Acceptance of Pain
The Secondary Moods (Compound Moods):
Hope (Orange) - [Mad + Glad] expectation, ambition, want - Anticipation of Pleasure
Guilt (Green) - [Sad + Glad] shame, contrition, regret - Conflict with Pleasure
Fear (Purple) - [Mad + Sad] panic, dread, distress - Anticipation of Pain
The Happy Will can utilize the Moods as needed without wallowing or fighting them.
NOTE: While Happy is usually represented in yellow, it is more accurately a brilliant, golden cascade of colors like staring into the sun, but only slightly less blinding.