USPS shipping cost

[francefm]

What makes that 2 equivalent parcels delivered by USPS to Canada and coming from the same state in US cost a big difference to the buyer?

[beautiful_times]

Are both sellers using the same USPS service?

First Class is the cheapest, but many sellers feel the need to use the much higher priced Priority.

Or is one seller using ebay's new Global Shipping Program? Which is also much higher than using First Class.