If you want to overwrite default plugins from 1.8.0 installation that's ok, you can do that without running into any issue. However if you overwrite 1.8.0 plugins on 1.8.1 you can and you will run into the issues. As we recommend to keep both software and plugins up-to-date, as the core can introduce a new class, which older plugins do not have, therefore you will get the error. 

Ross baby listen I am running 1.7.2 right and I am planing to update to 1.8.0. I have both:

Update pack and full installation pack.

I will use update pack to update the software right.

Now can I update plugins simply copying folders from plugins (1.8.0) and overwrite them on (1.7.3)?

Thanks

Yes, you can copy the plugin folders to overwrite 1.7.3 ones, after you run the core update from 1.7.2 to 1.8.0 

Awesome you are my savior Ross thanks so much.