The normal buckets sold in the local handy dandy lumber yard are 70 mil plastic buckets. They are thin and usually non food-graded.
On the other hand, quality pails are thick, sturdy and durable. They are also usually rated by UN, FDA, etc. Like the 6 gallon white heavy duty premium bucket below.
These white plastic buckets are heavy duty premium 90 mil. They have met the regulations of UN, FDA, USDA, UFC, and NMFC. Therefore they can be used for storing food and chemical. Made of HDPE (high-density polyethylene) material, the heavy duty pails are stronger than the other LDPE (low-density polyethylene) buckets. The pails can also be filled with hot items up to 190°F.
For more info on how to check if a pail is quality pail and well-rated, check out the video.