Also, both Catherine and TW made a choice. They choose to marry a husband that came with a LOT of obligations, scrutiny and public exposure. Kate made her choice in her 20's, after being with William for a long time. TW made her choice in her late 30's, with a mediocre acting career that was declining (Hallmark movies path), and after being married, and I'm pretty sure she was determined to marry him after their first date.
But Catherine embraced it all. We saw her grew her confidence and develop a natural ease on the job. TW never even tried. EVER. She was shocked that it wasn't always about her. She never learned (I LOL every time she pushes the smart one narrative), she was offensive, entitled and a bully for the people working with her. Funny thing is that we have proof of all of this, sometimes by her own words, reality show, podcasts.
One was in love with a man, and accepted the responsibility that came with him, and had a family that supported her (still do) through thick and thin; the other saw the man as (another) stepping stone on her pursuit of fame and money, and rejected ALL that came with him - on the way she also rejected ALL her family - even the ones that supported her and paid for her life for as long as she needed - that didn't fit some picture she was trying to paint, or contradict some of her "creative" stories.