Diana and Artemis are often worshiped as one. In essence they are very similar, but are in actuality two individual goddesses.

Artemis:

Being associated with chastity, Artemis at an early age (in one legend she was three years old) asked her father, the great god Zeus, to grant her eternal virginity. Also, all her companions were virgins. Artemis was very protective of her purity, and gave grave punishment to any man who attempted to dishonour her in any form. Actaeon, while out hunting, accidentally came upon Artemis and her nymphs, who bathing naked in a secluded pool. Seeing them in all their naked beauty, the stunned Actaeon stopped and gazed at them, but when Artemis saw him ogling them, she transformed him into a stag. Then, incensed with disgust, she set his own hounds upon him. They chased and killed what they thought was another stag, but it was their master. As with Orion, a giant and a great hunter, there are several legends which tell of his death, one involving Artemis. It is said that he tried to rape the virgin goddess, so killed him with her bow and arrows. Another says she conjured up a scorpion which killed Orion and his dog. Orion became a constellation in the night sky, and his dog became Sirius, the dog star. Yet another version says it was the scorpion which stung him and was transformed into the constellation with Orion, the later being Scorpio. Artemis was enraged when one of her nymphs, Callisto, allowed Zeus to seduce her, but the great god approached her in one of his guises; he came in the form of Artemis. The young nymph was unwittingly tricked, and she gave birth to Arcas, the ancestor of the Arcadians, but Artemis showed no mercy and changed her into a bear. She then shot and killed her. As Orion, she was sent up to the heavens, and became the constellation of the Great Bear (which is also known as the Plough).

     Artemis was very possessive. She would show her wrath on anyone who disobeyed her wishes, especially against her sacred animals. Even the great hero Agamemnon came upon the wrath of Artemis, when he killed a stag in her sacred grove. His punishment came when his ships were becalmed, while he made his way to besiege Troy. With no winds to sail his ships he was told by the seer Calchas that the only way Artemis would bring back the winds was for him to sacrifice his daughter Iphigenia. Some versions say he did sacrifice Iphigenia, others that Artemis exchanged a deer in her place, and took Iphigenia to the land of the Tauri (the Crimea) as a priestess, to prepare strangers for sacrifice to Artemis. Artemis is Apollo's sister, and Queen of the witches. She is the goddess of the moon, the herbalist, the midwife, the birthing woman, and the hunter. Artemis is an untamed wild woman who runs free with the deer and the hounds. She is the woman who runs with the wolves. She is "Mother of all Creatures." She is owned by no man, and thus she is "Forever Virgin."

     In Roman mythology Diana, goddess of the moon and hunt, and twin sister of Apollo, was essentially a goddess of the woodlands, her sanctuaries were commonly in groves, indeed every grove was sacred to her. She was chief hunter to the gods also the goddess of nature, and of the harvest. the guardian of springs and streams and the protector of wild animals

     In art she is typically shown as a young hunter, usually carrying a bow and arrows, like her brother Apollo. She would use her bow and arrows to punish  mortals who angered her.