differences between Enterprise User and Functional User or Task User

Differences between Enterprise User and Functional User/Task User.... Lets say,  1 Functional
User; irrelative of the Role Assigned to it, what basic or advanced global functionality/Option/Screen of AX2012 he will not be able to see or access when compared with Enterprise User.

Lets say for a client, I have a user "Machine Supervisor" whose role is not listed in 82 predefined roles in AX2012. My machine supervisor will be needing access to Production Cycle as well as access to Service Management Setups forms to perform his job.Now upon what criteria I will be deciding whether I need to purchase Enterprise/Functional/Task User?? there must be some boundaries (related to accessibility of forms/setup) associated with each CAL which gonna restrict me or bound me to choose between these CAL!!

you need to access CALMappingtool to find what two or three roles gets consolidated in your custom role "Machine Supervisor". If default roles get covered through task or any other type. you must decide on higher type user to make sure "Machine Supervisor" works.