What's the difference between the tablets?

I'm wondering what the difference is between the Intuos and Intuos Pro. Is the functionality the same? 
I'm a professional graphic designer and I use the tablet primarily for working in Photoshop and to occasionally replace my mouse when my hand gets tired. I'm a long time Wacom tablet user, but I haven't owned one since 2014. Any advice on which one to purchase is appreciated. :)