Aside from the main features, the Galaxy S9 is expected to come with some minor updates to other specs. The purported retail box of the handset suggests the following:
While the Galaxy S9 is shown to have a single 12MP rear camera module, information provided by @evleaks indicate that the larger S9+ will come with a dual 12MP rear camera module, more internal storage option (128GB) and more RAM (6GB).
It is also possible that Samsung might release a higher storage capacity model (e.g. 256GB or 512GB) as mass production of 512GB eUFS begun in December last year.
The Galaxy S9 handsets are believed to continue using thermal heat pipe designs to help keep temperatures more manageable, especially when running AI-centric features and other high-performance tasks.