Here's how you can tell the difference:
Canine Warts
Canine warts are also known as cutaneous papillomas and are usually found on the face, around the lips, on the eyelids, in the mouth and between the toes. Generally, dog warts are pale colored, benign (non-cancerous) and remain the same size and shape.
Dog warts may be the result of a viral infection or being over vaccinated. Some warts are caused by secretions of the sebaceous gland filling benign tumors. These types of warts need to be removed surgically. Eyelid warts are caused by small tumors that develop in the melibomium glands and also need to be surgically removed before they damage your dogs eyesight.
Cancerous Warts
Warts that may indicate skin cancer appear drastically different than benign warts. These warts are dark brown or black and usually appear around the face, eyelids or lips. Dark warts that change in size and/or start to ulcerate need to be checked and diagnosed for possible malignant melanoma.