The 61W charger does charge a litte bit faster. I ran my M1 Macbook Air down to 10 %, shut it down and charged it for 60 mins.
30W that came in the box: Charged from 10 % to 66 % in 60 mins.
61W Apple power adapter: Charged from 10 % to 78 % in 60 mins.
Not a dramatic difference, but noticeable. On the road, I would still prefer the 30W but at home, I wouldn't mind the extra weight and size of the 61W charger.