With very few exceptions all competently made interconnects and speaker cables will sound the same for very solid well understood technical reasons.
However when you replace these cables with a different / better one, you most probably will hear a difference, pretty much everyone does.
The question you have to ask yourself is this. What is causing the difference that I can so clearly hear?
Many enthusiasts will claim that, since the only thing that has been changed is the cables, the cables must be causing the difference, logical but flawed.
Other things have changed too, most importantly your expectation has changed and also your listening 'practice' will have changed too. These are known, proven effects that has an effect on what you hear, remove them from the equation by listening to a third party conducted blind test and the differences dissapear.
I understand that this is difficult to understand, the differences are so obvious that they must be real, is the usual reaction. I accept that such a test is quite difficult to arrange so as an indication of just how easily your ears can be fooled, take a look and listen to this.
https://www.youtube.com/watch?v=G-lN8vWm3m0