Unfortunately, there is no difference between the icons of popups vs visited websites.

well is there anyway to know if the site was visited or how long the site was used?

Hello,

I found this addon its has many option to manage the history: https://addons.mozilla.org/en-US/firefox/addon/form-history-control/?src=search

Case you want see more addon related: https://addons.mozilla.org/pt-BR/firefox/search/?q=history&appver=26.0&platform=windows

Firefox records the time you opened a page, but not the time you closed it, so there's no way to calculate how long you viewed it.

The sites you see in the history list were opened. Pages that were not opened will not appear in the list.

Why do you want to know which sites in your history are from pop-up windows?