I've read Tiny Habits, Atomic Habits, and a different book from Stephen Guise.
BJ Fogg's writing is much better organized than Guise's. Between Tiny and Atomic, I find Tiny covers much more conceptual ground on human behavior. The interplay of motivation, ability, and prompts is relevant even for behaviors that aren't habits. Also, Tiny covers much better the "why" and "then what" of these small habits.
Another book I would recommend that ties in nicely with Tiny Habits is The Willpower Instinct by Kelly McGonigal. She covers a lot of ground on the topic of why we do or don't do things. I think it could be a helpful debugging guide if you're struggling with a habit or behavior and need more depth than Tiny Habits.
Between all of the books mentioned though, just to be clear, Tiny Habits would be my pick if you were only going to read one. It's much more than just "make a habit of doing something really small". It's changed how I work on my own behavior and how I manage my team at work.
I never read his book, but I have taken a course by him via email. But yes, I believe they are the same thing. I think BJ Fogg has a more academic bent to it while this is a book from someone telling a story about what worked for them. I tend to like personal stories backed up with scientific evidence(I don't know if tiny habit is like that since I never read it). But, I like the practical implementation steps given in a personal story. What this book has over the stuff I was doing via email is that it is less complicated.
