Is it CodeIgniter or not?

Hello everyone!

I'm here trying to decide whether I will use CodeIgniter for this project of mines or not... now I'm basing my project on another one that's not really mines, I know, not so original from me to say that, but let me explain, this web app, was developed in a mysterious framework that I don't know yet what it is, something that I have been trying to decipher for a while, this web app is a CMS and it has almost the same app structure of a CI 2.x/3.x app... let me show you what I mean:

this is from the web app I don't know:


this is from straight of the codeigniter zip package:



this is the 404 not found from a web app demo using CI:



this is from the web app I'm onto:


So what are your thoughts on this? is the app I'm after for made in CodeIgniter?

(don't ask me to check what does the actual source files contains (class names, requires, namespaces. etc., etc.) because I'm not allowed to see that.)