# GetChanges(EntityManagerDifferOptions, AllocatorHandle)

> Generates a detailed change set for the world. All entities to be considered for diffing must have the EntityGuid component with a unique value.

## Definition

* **Type:** Method
* **Namespace:** [Unity.Entities](/engine/7000.0/script-reference/unity/entities.md)
* **Assembly:** UnityEngine.EntitiesModule

```csharp
public EntityChanges GetChanges(EntityManagerDifferOptions options, AllocatorManager.AllocatorHandle allocator)
```

### Parameters

**** (\[EntityManagerDifferOptions]\(/engine/7000.0/script-reference/unity/entities/entitymanagerdifferoptions)): A set of options which can be toggled.**** (\[AllocatorHandle]\(/engine/7000.0/script-reference/unity/collections/allocatormanager/allocatorhandle)): The allocator to use for the results object.

### Returns

| Type                                                                             | Description                                                 |
| -------------------------------------------------------------------------------- | ----------------------------------------------------------- |
| [EntityChanges](/engine/7000.0/script-reference/unity/entities/entitychanges.md) | A set of changes for the world since the last fast-forward. |

### Remarks

The resulting [EntityChanges](/engine/7000.0/script-reference/unity/entities/entitychanges.md) must be disposed when no longer needed.