Difference between Oracle 9i and 10g

9i is based on Internet technology and 10g is grid based one.

In 10g has some extra features are introduced comparing with 9i those are Automated storage management(ASM),
Automatic Database Diagnostic monitor(ADDM),
Automatic workload repository,
Automatic Checkpoint Tunning,
Streams Technology(STREAMS POOL),
Automatic SQL Tunning,Recovery Manager Enhancements(RMAN).
Built-in packages—(DBMS_SCHEDULER, DBMS_CRYPTO, DBMS_MONITOR)
Compile-time warnings
Number data type behaviors
An optimized PL/SQL compiler
Regular expressions
Set operators
Stack tracing errors
Wrapping PL/SQL stored programs

we can rollback after drop in 10g but in 9i can't rollback

10g is web based database management