I already made my case, but here's an elaboration:
To me, modding is fundamentally changing the game mechanics and requires actual programming, just changing colors and the like is customization. Having a .txt file where some fundamental numerical values are fixed, like the start and end dates of a Paradox game is a bit of both, however I generally don't do that either. My main issue with modding is that it almost never fits into a game atmospherically and alsmost always creates imbalances or makes the game more likely to crash. Options that come integrated into the game, like an editor for custom missions or things that you simply upload, like custom models or that stuff, which doesn't interfere with the game itself or even the campaign, that I do use sometimes.