When you see an anime broadcasted on your television, you expect to see the exact same thing on your screen when you proudly pop in your newly purchased disc or bring up your official download. Right? Not always.
Truth of the matter, by the time a show makes its way to DVD / BD, it may have gone through a few.. cosmetic changes. Some scenes may look a little altered. A character may appear more refined a second time around. What with the tight deadlines and crushing pressure staff are under, studios have been making a habit of releasing to TV the “not-so-finished” version or the “less pretty” version where it’s done just enough to be shown without utter humiliation and a terrible backlash from fans.
So the anime has reached the deadline for broadcast. Now this gives the
animation staff more time to go back in, make fixes to the shots, refine or
even completely redraw characters, and add shadows, pretty glow and hazy
effects, and other special effects.
Some say the changes seem unnecessary, others say, “I knew something was
different!” but when it comes down to it, the studios do what they feel
will make the anime more complete. After all, that’s what you get to take
home with you and keep. Forever.
Check out Kotaku’s article that talks more in depth about these before and after changes and with more examples -->