Pictures, descriptions or both are fine. You can specify preferred forms and what forms they adopt in particular circumstances.
The pale rider is when Death is typically seen as an old man riding a horse, leading another horse behind him. This form tends to be a gaunt man with pale skin, dry and stretched skin, and spindly bony fingers. He is a pale rider.
But his proper form is that of a tall, middle-aged man with a large set of thick feathered wings upon his back and a halo. This form is usually seen with a staff, a scythe, or an axe. In the other hand, he either has a clock or a broken hourglass in his other hand. Almost entirely clothed either in pure white or pure black, depending on the individual, each person will likely see his clothing and halo in a different light.
The Gardener
This form is similar to the first but more jovial and quaint, but often only seen in forests or wilderness areas away from people or towns that quickly. But, if looked upon by most, it will seem like a ghost planting ghost plants, from trees to flowers.
He may have other lesser appearances, but that depends on the person. He often changes his appearance to ease the passing and judgment of the dead. Be it an animal, plant, or person; he will take the form which may ease the dead or frighten them depending on his first impression.
Death
His last appearance is that which he is typically idolized as, and that is a skeleton with a dark cloak over his form.