I recently moved Dead Trigger 2 to my SD storage, but when I open my file explorer it still shows that Dead Trigger 2 is in my internal storage. When I checked my storage details it is showing only a 10MB difference, so I'm totally confused about the 'Move To SD storage' concept. I thought moving a 486MB game to SD storage is actually moving a 486MB game to SD storage, but my recent experience proves that I'm wrong. What is really meant by "Move To SD"?
There are different approaches to App2SD, which are briefly explained in our app2sd tag-wiki. The App2SD built-in to Android only moves parts of the app to SDCard, while other parts (e.g. the app's data and its dalvik cache) remain on internal storage. How much (or what percentage) gets moved varies from app to app – which is what you experience in the described case. Moreover, an app needs to explicitly support this mechanism.
There are different other approaches pre-installed with some custom ROMs (such as App2SD+), or separately installable on rooted devices (such as link2sd or Data2SD) trying to fill this gap; to completely move an app out of internal storage, one often has to use combinations of at least two of those tools.
Please see the linked tag-wiki for closer details.