Since we are not side-effects free, there is a difference between the first and the second.
You can read about it further here - Tree Shaking | webpack , but the general gist is this -
The first will load all files with side-effects defined in core (and will execute the free code in all of them) . If there are any, they will all be included. The second will only load “everything” from the scene file, which is technically only the scene itself.
It also depends what your output is, what packer you are using, what is your target etc’… Technically, not considering package size, they are the same - you will have a reference to the Scene class