Come down by the bucketful and Come down in buckets

Come down in buckets and come down by the bucketful are semantically related. In some cases you can use "Come down in buckets" instead a verb phrase "Come down by the bucketful".

Come down by the bucketful and come down in buckets are semantically related. You can use "Come down by the bucketful" instead a verb phrase "Come down in buckets".