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in 10g sysaux is new tablespace is present in 9i it is now present while in import and export any database in 10g impdp and expdp (data pump ) like facility is present
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.