The grain side is the smooth side of the leather which is mostly worn on the outside because of its appearance and its easy to clean qualities. The look of the leather is influenced by the pattern how hair, wool and plumes grow on the skin. Every animal has its own characteristic leather.
From male or female calf (max one year old) that are mostly nourished with milk. The leather with a fine grain is suitable for shoes and bags. Calf hides are 0,7 to 1,7m² and weigh about 12kg.
One hide’s average weight is about 30kg and is 2 to 6 m² big. Because of its size clothes and furniture coverings can be easily made without many seams. But it is as well suitable for bags because of its tensile strength. The best part of the hide is the back of the animal, because of the hides regular thickness. Bull leather can thin and lightweight or think and heavy depending of how many layers have been split.
Goat leather is more close and dense than sheep leather. That is why it is tough and soft. Goat leather has a visible line on the back. Compared to sheep leather goat hides are longer and more slim. Goat leather not covered with colour tends to stretch and widen that is why it is not suitable for tight clothes.
The pig’s bristles penetrate the whole skin. Because of that pork leather is more permeable for water than other leathers. Pork leather has a big variability in structure between side and core parts of the hide. Pork leather is mostly used for suede leather in many different colours. The very soft pork leather is suitable for leather shirts, vests, dresses and coats and it is the cheapest of all leathers.
A loose texture that contains a lot of fat.Because of this it tends to split and break. Sheep leather is characterized by many holes for the hairs that are placed in an irregular way. Contrary to goat leather, the natural grain of sheep leather is still visible after treatment of the leather. Characteristic for sheep leather is the very wide shape of the hide which is advantageous for further processing. Sheep leather is usually sold as Nappa or Suede leather and is mostly used for clothing.
(pics from Lederpedia; linked to their sources)