Ach, don't worry.

Textures always work, and the nodes are just like road signs to get them to the render engines. Some speak English, some speak German, and some speak Japanese.

Just ask an Italian to order a beer in China with a hot potato in his mouth and speaking Spanish. LOL.

The node system is more like a bunch of translators to get the render engines to understand what to do.

It 's like an obj file. All the polygons are there, but they are "lost" without the UV_Map telling to the texture what texture part should go where.