Hi Mark,

Welcome to the forum.
It would be more time / resource consuming using conditional formatting (formulas)... hence suggest you to be open for a macro where after listing down countries in page 1, macro will check (ctrl + F) if that name is available in sheet 2 and if yes, it will highlight the name in sheet 1

Regards,
DILIPandey

<click on below 'star' if this helps>