Oracle Basic : Oracle 10g vs Oracle 11g

Top few features to list - Difference between 10g and 11g

1.Simplified and improved automatic memory management

2.New fault diagnosability infrastructure to prevent, detect, diagnose, and help resolve critical database errors

3.Invisible Indexes

4.Virtual columns

5.Enhanced security for password-based authentication by enabling use of mixed case in passwords.

6.Tablespace-level encryption

7.Ability to online redefine tables that have materialized view logs

Difference between 11gr1 and 11gr2

Oracle 11gR2 is the second and terminal release of the Oracle 11g database.
The common theme for this release is "Consolidate. Compress. Control.".

New Features:

1. Oracle RAC One Node
2. Improved data compression ratios (up to 20x).
3. Ability to upgrade database applications while users remain online.
4. New ease-of-use features that make Grid computing more accessible.
5. deferred segment creation new feature in Oracle 11gR2
6. In-Memory Parallel Execution
7. Auto Degree of Parallelism (Auto DOP) and Parallel Statement Queuing
8. Significant Performance Improvement of MV On-Commit Fast Refresh
9. Database Resource Manager Instance Caging
10. Hybrid Columnar Compression

(source - internet)