No, it's not the same, just more. The architecture is very similar, but the system has many custom optimizations (so does the Pro, but they're different custom optimizations), it's balanced differently, and a lot of work went into making it not just highly efficient, but also power efficient with a small physical and energy footprint. It also takes a different approach to making sure it's compatible with base Xbox One software. Digital Foundry had several insightful features about it, so I suggest you check them out.
Yeah, while I don't necessarily agree that AMD gives anyone confidential info about their other customers' products, that's how some business deals go down in my experience as well. It's not how it should be done, of course, but it often is. And when years later you get insider accounts about how these big wigs conducted their business, it's rarely all by the book.