What is the difference between watcher and attendee?

[Rumceisz]

Hi,

could you please clarify the difference?

Thanks,

Rumi

[Nic Brough -Adaptavist-]

A watcher is a user who has chosen to watch the issue.

An attendee, is, well, probably a user who you name in a custom field called attendee.  But we don't know what you've configured to make it available.  (JIRA's built-in user fields are Reporter, Watchers and Assignee, I don't know where your attendee has come from)