Import Blu-ray confusion, timing

[jeffm2016]

Hello, i just started getting into imports and region free disks. I get region free is copyright and not the same as if its ntsc or pal. Some postings mention how import shows may have timing thats off in us players due to pal. I thought for awhile it affected tv only but then was told movies too. Then recently was looking into a tv show (star wars clone wars) and was told there was no difference between us and uk. (Maybe there are exceptions like in cartoons or something.

So are there rules when the timing are the same or not? Or things to look for in the disk? Have i been given wrong information at times? How do I know if an import (im in the states) will have timing thats off.

I get it might not always matter based on personal
Preference but there are times id like to know what im getting and how to figure it out.

Thanks!