I think the ODM is updated too frequently, so it will always show differences.
I think you can detect inconsistencies between ODM and VGDA, but I'm not sure how. You should read the VGDA with readvgda hdiskX or lqueryvg –p hdiskX –At, and then check with odmget against the ODM.
For other ODM entries (devices, software, etc...) I don't know if there is a way to check inconsistencies.