The group migration product supports the migration from a unified group to a unified group or a shared mailbox. Depending of your choice for the target recipient type, the migrated data will differ:

To a Unified group

With this choice, the migration tool will migrate:

  • Conversations (mails, inbox only)
  • Documents
  • Calendar entries
  • Permissions (Owners and members, within the per-processing task)
  • Notebook (next version)
  • Site (Pages  and Site contents: next version)
  • Planner (next version)

To a Shared Mailbox

This choice offers the lowest fidelity for your migration. Only the Conversations (mails, inbox only) and Calendar entries are migrated. The permissions will be migrated within the creation of a mail enabled security group during the per-processing task

See this article to know more about the pre-processing task: http://kb.cloudiway.com/group-migration-pre-processing/