What is the difference between SAP BW 3.5 and 7.0?

SAP BW 7.0 is called SAP BI and is one of the components of SAP NetWeaver 2004s. There are many differences between them in areas like extraction, EDW, reporting, analysis administration and so forth. For a detailed description, please refer to the documentation given on help.sap.com.
1. No Update rules or Transfer rules (Not mandatory in data flow)
2. Instead of update rules and Transfer rules new concept introduced called transformations.
3. New ODS introduced in additional to the Standard and transactional.
4. ODS is renamed as DataStore to meet with the global data warehousing standards.And lot more changes in the functionalities of BEX query designer and WAD etc.
5. In Infosets now you can include Infocubes as well.
6. The Re-Modeling transaction helps you adding new key figures and characteristics and handles historical data as well without much hassle. This facility is available only for info cube.
7. The BI accelerator (for now only for infocubes) helps in reducing query run time by almost a factor of 10 – 100. This BI accl is a separate box and would cost more. Vendors for these would be HP or IBM.
8. The monitoring has been improved with a new portal based cockpit. Which means you would need to have an EP guy in your project for implementing the portal !
9. Search functionality has improved!! You can search any object. Not like 3.5
10. Transformations are in and routines are passe! Yes, you can always revert to the old transactions too.