There are no standard categories for websites. You can call it a gallery website if you like. There are lots of gallery plugins for WordPress, and lots of scripts you can use on any site as well. Perhaps describe what you actually need the gallery to look like. (The links you posted didn’t clearly relate to your situation.)
This CMS is mostly for photos: Koken It can be a bit confusing to use at first but not to bad when you get the hang of it. When I tried it the admin section would not work in internet explorer but it’s eay enough to install another browser.