using versus out of scope

[C# Programming]

End Google Ads 201810 - BS.net 01 --> How does this:

using (MyObj myObj = new MyObj(); ) {
myObj.DoSomething();
}

differ from this?:

{
MyObj myObj = new MyObj();
myObj.DoSomething();
}

I have been using the latter and I'm just wondering if it is more correct to use the former?