What is the difference between "Reply" and "Public Comment" in a ticket?

What is the difference between "Reply" and "Public Comment" in a ticket?

Hey, my company is thinking about switching to Zoho Desk but we do not understand the difference between the "Reply" and the "Public Comment" feature. When should we use which? And why? What is the difference between them?

Thank you for your help!

Kindest regards,
Glenn