Tin is a low-melting crystalline metallic element that is malleable at room temperature. Tin is typically extracted from a mineral called cassiterite, a compound of tin and oxygen. Tin's basic refining process makes it appealing for manufacturing. Tin also does not corrode easily, which is why it is useful for cans. A modern tin can is actually made from steel coated with a very thin layer of tin to prevent the steel from corroding.
Aluminum is also a metallic element. Unlike tin, which only makes up 0.001 percent of Earth's crust, aluminum is abundant, making up 8.2 percent. However, aluminum is much more difficult to refine and is always found in compounds in nature, usually potassium aluminum sulfate or aluminum oxide. Different processes have been developed over time to refine aluminum, each increasingly more efficient. Aluminum cans are made from alloys of aluminum, and these alloys are notable for being strong and very lightweight.
Tin cans are heavier than aluminum cans and are more durable. Tin cans are also highly resistant to the corrosive properties of acidic foods, like tomatoes. However, tin cans are less efficient for recycling than aluminum.