[jQuery] a question about the easing types in interface plugin

[Guapo]

i checked the demo page on the interface website. but i donno what the
easing types really mean. on the demo page, i selected an easing type
and click the "animate" link.  the top emement just move left to right
or right to left. I can't see any difference between them. who can
explain it to me, great thanks!