I'd feel quite bad since my son was the same age and wasn't talking much, let alone identifying animals. The constant showing off and comparisons by my in-laws led to us taking him to a speech pathologist and to his pediatrician for an eval, to make sure he had no delays (he doesn't have any).
The other day, my wife realized that her niece (now over 2) couldn't identify the exact same animals, when they were in a different book, or using plastic models. She had learned the book, but didn't understand the concepts.
I've learned my lesson about comparing milestones. I suppose a professional may be able to do meaningful comparisons, but the average parent or grandparent cannot.