An Animation is like a video player.
Play, pause, seek, speed it up, slowmo and even play it in reverse.
Associated with a Timeline, which it uses like a clock, to figure out what time it is.
You can give an Animation "effects", for example KeyframeEffect.
new Animation(effect , timeline );
An effect is an item it plays in its' timing hierarchy.
You can use KeyframeEffect, GroupEffect and SequenceEffect.
The source of time it uses.
Could be a clock, random values, scroll position or even input from a touch gesture
Currently Level 1 Web Animations only specifies the global clock, document.timeline, but in the future we should be able to have custom timelines.
var effect = KeyframeEffect || GroupEffect || SequenceEffect || null;
var timeline = AnimationTimeline || null;