The Arums come in shades of white / cream and light pink whereas the Callas are mostly orange shades. These plants are actually regarded as weeds through much of the world.
Georgia O'Keeffe was most famous for using the Arum lily as a subject matter for many of her most famous paintings (see below). As the Arum lily is said to resemble the female genitalia, many artists have used this theme to represent female sexuality.
Another famous series of paintings using the Arum lily as the main motif is Diego Rivera's Flower vendor series painted in 1935 (above right).
My painting of the Arum Lily (above left, 2004) was heavily influenced by Georgia O'Keeffe's style. It is one of my earliest paintings and sold a few years ago. I was drawn to the vibrant colour of the foliage more than anything else.