"Freckles and moles have two things in common: there is a genetic tendency to get them, and both are darker than the surrounding skin.
However, there is one big difference. Freckles have zero potential for malignant transformation."
On the other hand, this article says "Unusual-appearing freckles may become malignant skin cancer."
Furthermore, this article says "Although there are many different types of cancer, they all start because of cells that are growing abnormally and out of control. Cancer can start in any cell in the body." The bold font is in the original.