Wolves (and seals) are more like other wolves, than any other animal. Also, they are all closely related by morphology (form and structure, including shape, color, pattern, bones, organs). Skulls and teeth are popular for distinguishing one genus from another.

i.e.

There are Grey Wolves (Canis lupus) and Red Wolves (Canis rufus). They are separate species but they are both 'wolves'.

i.e.

There are Leopard Seals, Grey Seals, Elephant Seals etc. They are all separate species, but all are still 'seals'.

So what makes a wolf a wolf and a seal a seal etc?

Thanks