Dear,

1 - Migration is not equal to Scheduling.

2 - Migration : moving the work from old position to new one, position may be Host,VM, or datacenter. migration has many type (such as ., online-offline).Migration may use in scheduling.Load palance is one of reasons that lead us to migrate.

3 - Scheduling: setting tasks at location(i.e., VM-Host-Datacenter...) with order in time. but setting VM at host can be called provisioning,Setting tasks at VM is called allocation and if we link it with time or order to execute so that is scheduling. 

Best wishes,

Regards.

Scheduling is decision making about allocation

Priority scheduling is a type of scheduling

Migration is an operation that you may need to perform to implement the decisions of scheduling. However scheduling may not be the only reason behind migration.

• All these concepts are not called scheduling, however they are related to scheduling.
• Priority scheduling may not be just sorting, priority may contribute to an objective or constraint 
• Other than load balancing packing may also be the reason behind migration, even legal/privacy, data locality related reasons may include
• Scheduling may not be optimum, Often a sub-optimum schedule is chosen
• Yes, objective of scheduling is to find an optimum or sub-optimum assignment or allocation, but dispatching is an operation that may take place right after scheduling decisions are made

dispatching tasks to VMs in an optimum way and placing VMs into PMs in an optimum way are two problems, However you may solve the both in one algorithm. So scheduling is just decision making (nothing happens), provisioning, allocations, dispatching are the operations that happen after taking decision.

thanks