Color.
And I agree with the square crop, or at least cropping the right side. But you've already stated that you did that intentionally because…reasons.
In other news: *I* have a cat named Hobbes too! She's about 17 years old. Her sister, Calvin, died a couple of years ago.
Yes, females. Named Calvin and Hobbes.

I got them for my boys the spring after their dad had left. I *specifically* asked the lady if they were males, and she said yes. She brought them by the house (AND they were free), and I just didn't really think to CHECK that little matter at the time. By the time I realized that they were NOT boy cats, my kids had already named them and I didn't have the heart to tell them their boy cats were girls.

They were in their teens before they learned the ugly truth.