Tubers can have high potassium, carotene, and a little protein which makes them "first choice" carbs. White rice lacks these but contains nothing offensive either (after cooking). The only reason to avoid rice would be if one is doing VLC but otherwise I view potato and rice as interchangeable depending on the cuisine, e.g. roast beef and cabbage = potato; stir fry or curry = rice.
Quantity is not really different. H2O fraction of baked potato is about 65%, boiled potato 80%, cooked rice 70%. I consider a serving to be 1 medium tuber or 4 tablespoons raw rice (+1/2c water).
Lots of: urban hiking, cycling, sprinting
Lots of: fresh meat, seafood, eggs, organs, tubers, starchy fruits, low-energy plants, meat fat, dairy fat, oily fruits
Some: cured meat, dairy protein, sweet fruits, rice, peas, tree nuts, oily seeds
Minimal: soy, refined proteins, sugar, liquid carbohydrate, grains, beans, refined oils, peanuts