Hello. I'm not sure :), but we can use pkg version -t to find out how big or small the port version is. pkg version -t 1.20.2_9,2 1.22.0_10,2 is <.
www/nginx-full is the sl@ve port of the m@ster port www/nginx. So, changes in the distfile version will automatically follow. But then the sl@ve port tends to forget to set PORTREVISION back to 0, so it would appear that the version number is followed by a version number that is hard to tell which is newer :) maybe :) Regards.