How about browserstack for selenium?

Sir,

Have till date worked on selenium scripts on local machine.
How different is that when scripting is done on [b:1hv3321a]browserstack[/b:1hv3321a]?

Are there some scripting [libraries] which are not supported on [b:1hv3321a]browserstack[/b:1hv3321a]?

Could you also provide me a reference of selenium with [b:1hv3321a]browserstack[/b:1hv3321a]..