Difference between Calm App Subscription Prices

Hi,

I was wondering if anyone knows what the difference is between the Calm app subscription prices/options? I signed up for a 7-day free trial of the app, and the Apple subscription settings have automatically selected the $76.99 Calm Premium annual subscription option to auto-renew my account (if I don't cancel before the 7 days are up). I do see on the subscription page that there are cheaper annual options, such as Calm Premium (1 Year) for $51.99, Calm Premium (1 Year) for $59.99, etc.

Does anyone know why Apple automatically selected the $76.99 option for my account? Does this have anything to do with the fact that I am in Canada/currency? If not, does anyone know if there is any difference between these different cost options, or can I just select the cheapest one?

Thank you for your help!