Well, there is not MUCH difference between 10g and 11gR (1) RAC.

But there is a significant difference in 11gR2.

Prior to 11gR1 (10g) RAC, the following were MANAGED by Oracle CRS:

• Databases
• Instances
• Applications
• Node Monitoring
• Event Services
• High Availability

From 11gR2 (onwards) it’s completed HA stack managing and providing the following resources as like the other cluster SOFTWARE like VCS etc.

• Databases
• Instances
• Applications
• Cluster Management
• Node Management
• Event Services
• High Availability
• Network Management (provides DNS/GNS/MDNSD services on behalf of other TRADITIONAL services) and SCAN – Single Access Client Naming method, HAIP.
• STORAGE Management (with help of ASM and other new ACFS filesystem).
• Time synchronization (rather depending upon traditional NTP).
• Removed OS dependent hang checker etc, manages with own additional monitor process.

Well, there is not much difference between 10g and 11gR (1) RAC.

But there is a significant difference in 11gR2.

Prior to 11gR1 (10g) RAC, the following were managed by Oracle CRS:

From 11gR2 (onwards) it’s completed HA stack managing and providing the following resources as like the other cluster software like VCS etc.