TSATOP is different because teaches you to actually quantify the value delivered to the customers. i.e., how much, in real dollars, is 100% uptime going to save us over 99.99%?
It seems like a small difference, but its not: 100% uptime unlocks new business models that don't work with "only" 99.99% uptime (e.g., banking software or API companies). That's what TSATOP really explains - how to quantify the seemingly minute differences in your offering, and how to communicate that value to the customer so that you can charge accordingly.
To use an example actually from the book, how much money will a DNA testing kit that requires 10% less sample material be worth to a customer?
Well, first that depends on who the customer is - its a lot more valuable to a pharma company than a university, for example. But how much more? The book would do something like calculate the number of new drugs the pharma company can release each year based on having this better DNA testing kit, and calculate how that affects the customer's bottom line. Eventually this would result in something like: every time you use our product instead of our closest competitor, it puts $50 in your pocket.
Seth Godin's writing is awesome for motivation and to get your brain moving, but this book really drills down on the nuts and bolts of pricing, and provides templates and worksheets for performing your own Economic Value Estimation of your product. Both are really useful, but this one is more like a textbook, whereas Seth's is more like a (very) motivational speech.