Companies that operate in multiple regions sometimes use these buttons to make language-specific or region-specific content available. For example, some cars may only be available in some regions or may have different branding. Another example is how the Apple Store has region-specific editions. Also Netflix filters the library by region.

A lot of eCommerce websites will only ship to/operate in the U.S. for a variety of reasons (business registration requirements, consumer protection laws, currency exchange, international shipping, etc. Hence websites like newegg.com and newegg.ca.

Certain product lines or pages will be missing, or the details will be less informative on the Canadian/International regionalized website. Not to mention most online shops will only ship to the US.