The three type of big onions are red, white, and yellow.
Yellow is best for cooking.
Red and white are best raw.

Bunching onions are also known as green onions.
You can buy and grow bunching onions.
Or, you can pull regular onions when they are small.

There is also an onion called the winter onion.
The winter onion grows in bunches and is a perennial.
They come up and seeds grow up at the top and if you leave them, they will drop the seed for the next growing season.
These onions can be eating fresh or cooked and are smaller in size than bulb onions.
The later in the season they are, the tougher they are so that is something to keep in mind if you do buy or grow them.

If you do have a garden and grow onions, any onions that have been grown the year before may start to sprout after several months.
You can replant those for more onions.
They will grow and bulb.