I'd say a bucket can hold a larger volume of water than a mug. Actually, a number of things can hold a larger volume of water than a mug, like a tank or even a swimming pool. A bucket, for instance can hold 10 mugs of water and 2 buckets will hold 20 mugs of water. For obvious reasons, a bucket or a tank is bigger than a mug. Thus, it can hold more water.
