Seeds vs Grains
A seed is defined as an embryonic plant covered in a seed coat, often containing some food. It is formed from the ripened ovule of plants after fertilization. Seed formation completes the reproduction cycle in seed plants, which begins with the growth of flowers and pollination. The embryo grows from the zygote while the seed coat grows from the ovule rind.
A grain is a small edible fruit, usually hard on the outside, harvested from grassy crops. Grains basically grow in a cluster on atop the mature plant and they include wheat, oats, rice and barley. Because grains are generally grown on a large scale, they are considered staple crops and they are the number one energy providers worldwide.
Technically speaking, we can refer to a seed as an ovule containing an embryo within, while a grain is a fusion of the seed coat and the fruit. In some grains like peanut, the shell can be separated from the fruit to reveal the seed. However, in other grains like corn, the seed coat and fruit tissue cannot be separated.
A seed typically has three basic parts which are the embryo, seed coat and the endosperm. Obviously, the embryo is the most important part because it is its cells that eventually differentiate and grow into the various tissues that constitute the plant eventually. The seed coat and endosperm simply provide support, although they are critical to the embryo’s development.
Grains provide food mainly from the fruit part, for instance, food from wheat grain is derived from the ground fruit, which is a part of the grain. In crops like millet, it is actually the seed that has properties very similar to those of the fruit part of the grains, and that is why it is handled as a grain in culinary terms.
In seeds like peas (and pea-like seeds), sections of their embryo have very mealy properties when they are dried comparable to those of grains. These could be ground to get flour which can be very similar to the one taken from typical grains in culinary terms.
Summary
1. A seed is an ovule containing an embryo while a grain is a fusion of the seed coat and the fruit.
2. Typically, seeds are planted to grow plants while grains are harvested for food.
3. Grains provide food from the fruit part while seeds mainly provide food from embryo parts.