Smith Corona made a lot of typewriters in the 1990s (this one was made in 1994) with lots of tiny differences between them--some of them not even noticeable. This particular typewriter is very much like the SD300. It's heavy enough to be called a desktop, but light enough to be portable.
The memory on this typewriter works the same as the SD300. You can store up to 7 documents internally, but there is a character limit. I'm not able to find out what that is, but it's probably not something anyone would test--you should be able to store enough characters to fill out an entire page.
This typewriter also looks simpler than the SD300. You can either use it as a regular typewriter (by swiching it to 'type') or use the memory features (by switching it to 'mem').