Nice article! Having gone the other direction (knowing Oracle and needing to support SS), something like this would've been helpful to me a few years ago. But I'd like to clarify a point or two.
"Having a database is not necessary to run an instance." While technically true, the only practical reason I can think of to have an instance w/o a DB is when creating the DB. When creating an Oracle DB, the instance must first be started (in "nomount" mode). The next step is generally the "CREATE DATABASE" statement.
Redo logs -- plural. The required minimum is 2 and it's common to see 5, 10, or more of them in a DB. When one fills to it's DBA-defined maximum, the next one takes over. In NOARCHIVELOG mode (SS's "SIMPLE" recovery), the logs switch seamlessly. In ARCHIVELOG mode (SS's "FULL" recovery), the full log must be archived off (backed up) before Oracle will use it again. If it's not and all redo logs fill, the DB pauses everything until it is. There is no truncating of the log -- ever!
Great stuff! I'd like to see more of this, especially at the object level. The interleaved nature of index storage in SS (Oracle's indexes have storage independent of their tables) still gets me...