In Firesub checklist a copy of a template that can be performed, checklists are always created using a template. You "start" a checklist from a template.
A checklist contains tasks that can be marked as completed. It also has people assigned to the checklist. The people assigned is the people who completes tasks and marks the whole checklist as completed.
When a checklist is started from a template all tasks and properties of the template is copied to the new checklist. Depending on the permission settings on the team and template you can add additional tasks and change properties of a checklist and it will not change the original template.