When performing Chatter migration:
- Selecting Attachments will include Chatter Attachments.
- Selecting Inline Images will include Chatter Inline Images.
PS: View Mass File Migrate Salesforce file migration app on Salesforce AppExchange:
https://appexchange.salesforce.com/appxListingDetail?listingId=e9874a66-2001-4e3d-8a29-3a2ed7f584c4