I've googled it and what people are saying is that the Blender Post-Production is much harder to learn but is as powerful as Photoshop and After Effects, while the Adobe 2D software solutions are more "expensive".
(I assume those statements came from before the Creative Cloud release)
But my question is: Is there an actual difference between those?
Like, does Blender take into account mutliple other things that an external 2D software like PS/AE can not and thus gives me an image with a higher quality?
It's always an imperfect exercise to compare complex software to deduce the differences between each. How you define "post production" is also a factor. Let's say you're asking according to the context of this video where post production means color adjustment, vignette addition, and other simple photo manipulations.
In that context, I can use Photoshop and Blender's Nodal Compositing to achieve the exact same post-processing effects. At that point the choice becomes which UI do I want to work with. Each has subjective pros and cons, but for you question, they are equals imo.
However in a broader, more complex Post Processing context where artists are rendering multi-pass/layer .EXR's, adding artificial depth-of-field, post processing animations, etc I find Blender to be more apt for that than Photoshop.
It's a big question that's hard to answer concisely but I hope that helps.