Purchase Order in CRM vs. Inventory

Purchase Order in CRM vs. Inventory

Question for anyone familiar. We recently started using the PO function in the CRM. But I am not able to get some of the reports that I need and I need to make each line item have its own status which also seems to be an issue. So I guess I have 2 thoughts/questions on this. 
1. Why are there 2 different PO systems that while they have the same function they potentially don't have the same reporting ability?
and
2. Why not just have it all in the CRM? If I start using the Inventory App, are my vendors going to get updated with PO info or will I constantly have to run that second app?

Thank you for any insight.