Sharepoint workflow create task properties: when to create fields and when to create depepndency properties ?

Question

Hi all

I'm new to SharePoint workflows.

When creating a new task and assign the TaskId I have two options:

1. To create a new field to hold the TaskId
2. To create a new property to hold the TaskId.

The new property is a dependency property.

My question is what is the difference between assigning the task as a field or as a property?

Thanks