As mentioned in CRM Sdk, below is the major differences between Data Migration and Data Import.
Data migration and data import use common entity model and messages. However, there are some important differences in the feature sets of the two operations as shown in the following table.
|Feature||Data Migration||Data Import|
|Import data into Microsoft Dynamics CRM||Yes (Only the system administrator can migrate data in the offline mode.)||Yes (All users who have appropriate permissions can import data.)|
|Import data into custom entity types and attributes||Yes||Yes|
|Use multiple source files that contain related data||Yes||No (You can only import one file at a time.)|
|Assign entity instances to multiple users||Yes||No (All entity instances are assigned to one user.)|
|Update existing entity instances||No||Yes|
|Detect duplicates||No (You can run duplicate detection after you migrate the data.)||Yes|
|Delete all entity instances associated with one job||Yes (Use bulk delete feature.)||Yes (Use bulk delete feature.)|
|Automatically map data based on column headings in the source file||No||Yes|
|Set the value of the createdon attribute for the entity from source data||Yes||No|
|Customize Microsoft Dynamics CRM to match source data||No (Custom entities and attributes can be created by Data Migration Manager.)||No (Customization must be done before import.)|
|Apply complex data transformation mapping||Yes||No|
|Import state and status information||Yes||No|