Online game - distance while running?

Hello we're playing with the woman FFXIV. And we play on the same notebook and on the same internet. If we meet in the game and run forward at the same time, it will be displayed to me afterwards. When running, we run on my notebook at the same time and when I run her on the notebook, I run after her. Why is that out of sync?

In some games this is never synchronized because they receive different data packets.

This is called latency, the movements of the one have to go to the server and he has to let a corresponding figure follow you (quasi a remote controlled npc) and that takes a second