http://www.freediff.com/ you can try this, it locates and points out the differences between 2 files

I know there's a better one that people here have used to find the diffs between cfgs but idk what it was exactly

unfortunately youre going to fuck up straight in the beginning, i tried using various text differentiating sites and programs, but all of tf2 configs are written similiarly but just formatted differently, so there is no way to actually differentiate them except for formatting them manually, but that would take a fuckton of work to do

You can write a new config file (host_writeconfig or something) after executing them in game and them compare. Should be formated in the same way.

I think notepad+ has a built in function for that but I'm on mobile rn and cannot confirm

thats one of the apps i used, but as i mentioned, these cfg are formatted slightly differently, so about from string 5 you are differentiating absolutely nothing

shoras came up with probably the best solution: execing each of these cfgs separately, writing new cfgs and then differentiating absolutely equally formatted configs with an app or whatever

also watch out for non-existent anymore commands, there are a few, for example: "cl_preload". any non-existent commands will be shown in the console as non-existent, so before writing a new config, remove them from executable config

Here's what I would do.

1. Make a copy of both configs
   
2. Open in a text editor such as Atom with a sort lines plugin
   
3. Sort both configs alphabetically
   
4. Optionally: delete all comments and empty lines
   
5. Open in DiffMerge to see differences

that wouldnt work as planned, since configs have different amount of actual "command" strings and description strings, so you would end up with the whole diff screen lit up in red colour no matter what you try, the only way to do it is how shoras said