What a great question!
I have found that many young children have difficulty distinguishing one type of animal from another. My son learned the word "dog" very early on (both spoken and signed). He used the word dog to describe cats and wolves and foxes.
I have witnessed many young children make similar mistakes: Cows/horses, snakes/lizards, cats/dogs.
My son is also very interested in animals. He loves animal shows (such as Wild Kratts), adored the Omaha Zoo, and is very observant when it comes to spotting animals (real or depicted).
So, I decided to use his confusion/misuse of the terms as a learning opportunity.
Every now and then I'll sit my son down in my lap when I'm using my computer. Then, I'll do a Google Image search for different animals. It's best to have Safe Search enabled, and set the options to search for Photos.
Then, we'll go through and look at the different animal types. For "dogs", there's such a variety! So, as we looked at the different breeds I tried to find common features to help him learn (big ears, long snouts). Some dogs, like pugs and bulldogs, obviously don't fit! For these, at least my son was getting exposure to different breeds.
After dogs, I'd switch to different animals. I really wanted him to learn the difference between dogs and wolves, because I noticed him calling my wife's wolf statues dogs. I showed him a lot of pictures, and pointed out how their ears and snouts are always pointy.
Something I did worked, because he not only started calling the statues wolves instead of dogs, but he's also pointed out other wolves correctly when we hadn't been exposed to them before, so we never prompted him on the correct term.
I also showed him foxes, and pointed out how they're smaller (like cats), and red/grey. We don't get exposed to them much, so I'm not sure he's learned foxes, but I do know he's learning that not all animals are the same.
You may also benefit from this informal training. Look closely between animal types, and try to see the differences. Some things to look for:
- Size/shape of ears (pointed vs rounded, donkeys have much longer ears than horses)
- Ears floppy vs upright (cats have upright ears, many dogs have floppy ears)
- Length of fur (wolves have thicker fur than many dogs)
- Color of fur/skin (pandas have black/white coloring, bears are solid)
- Length/size of nose (dogs have longer snouts than cats, usually)
- Comparative size of animal (bigger than X, but smaller than Y)
- Length of body (many rats have longer bodies than mice)
- Size of head (horses have big heads compared to deer)
- Types of markings (red foxes have black tipped ears and feet)
- Types of limbs (hooves vs paws)
- Habitat (turtles in/near water and tortoises on dry land)
Once you understand the difference between animals more clearly, you'll likely be able to more easily spot where the illustrator took artistic license in your child's book. You'll be able to point on the aspects that make one animal stand out from the other, even if it's minor. I made a very minimalistic illustration to show some differences (I might make a better example later when I have a mouse instead of a touchpad).
If you can verbalize the difference between these animals, and correctly guess what they are, then you're on the way to improving the experience of reading these children's books.
1) Fox 2) Wolf 3) Dog
In the meantime, I'd continue to use the terms given in each book. While some artist's depictions of the animals might not be terribly clear to you (even if you brush up on animal identification skills), it's still teaching your child that even though animals look alike they are different. Eventually, their minds will come a conclusion and be able to identify different animal types. The age this happens will depend on not only each individual child, but also the types of animals they're differentiating (wolf vs. dog is harder than cat vs. dog).
Or, in some cases, they might never learn at all. While I'm pretty animal-savvy, I can't ever identify a gerbil from a hamster.