Are dogs and wolves the same species?
Yes, in a sense, because dogs and wolves can interbreed.
But the story is more complex. It's long been thought that the grey (or timber) wolf is the ancestor of dogs.
Controversial new research suggests that dogs and grey wolves are probably both descended from a common ancestor wolf, now extinct. They had the same grand parents, n times removed.
Modern dogs and wolves share 99% of their DNA (I think it is), but that small difference seems to be responsible for (amongst other things) a big change in behavior.
Dogs want to be ordered. Wolves make up their own mind.
Tell a dog 'no' and it may obey.
Tell the most human-friendly wolf 'no' and it will ignore you.
Like a cat, in fact.