Update IB Asset Data- what are the different methods?

Summary:

We want to mass update a list of IB Assets- update a value under a custom field or a DFF added field.

Content (please ensure you mask any confidential information):

What are the optional tools? I read about FBDI and also using Import Management- I could not understand the difference between the two.

Also, I did not see any reference how to add to the template our customer fields.

Version (include the version you are using, if applicable):

25A

Code Snippet (add any code snippets that support your topic, if applicable):