Difference between oracle 9i and oracle 10g?
A lot of differences this is my take on them:
8i -> 9i - Real Application Clusters, PL/SQL enhancements,
XMLType enhancements
9i -> 10g - ASM space management, tracing and diagnostics,
DML error logging, async commit, more PL/SQL changes, table/column
encryption, restore points
10g -> 11g - Probably best to point you to technet on that
one.