But white is usually more acidic, so works faster.
If you're feeling adventurous you can use neat hydrochloric acid to clear really bad limescale. That gets rid of it in seconds. Great for water heater matrices and taps. Not sure I'd try it in my dishwasher though.
I found white vinegar did a great job when my dishwasher was having similar problems, and much cheaper than a new dishwasher!! It also worked great when I needed to descale my iron.