AX 2009 to Dynamics 365 Upgrade
Dynamics 365 Finance & Operations offers considerably more functions and flexibility than Dynamics AX 2009 in the areas of production, inventory, warehouse management, and financial dimensions. That means you’ll have more functionality once you move to Finance & Operations.
To ensure you leverage that new functionality effectively and achieve full user adoption, discuss these changes with your Dynamics Partner at the start of the implementation process.
For the same reason, user adoption for people accustomed to AX 2009 will take slightly more effort.
AX 2012 to Dynamics 365 Upgrade
Businesses on AX 2012, 2012 R2, or 2012 R3 will find the move to Dynamics 365 Finance & Operations somewhat easier. The vast majority of the functionality in Finance & Operations already exists in AX 2012, especially in R2 and R3. So, if your business processes and needs are largely unchanged from when you configured AX, your partner can mostly take your existing business configurations and migrate them to the cloud.
Admittedly, the Finance & Operations interface is different than the AX interface, but after a day or so of adjustment, your staff will be able to find all the functions they are used to.