Well, the iPhone 11 has a bigger case, 6.1 inches (about 15.5 cm) screen diagonal and the iPhone 11 Pro 5.8 inches (about 14.6). The iPhone 11 is also a bit thicker than the Pro. So the 11 Pro is a bit more compact and a real powerhouse for its size. But, since both iPhones have the same internals, except for the battery, there's not much you can say about the weight. They also used cheaper materials in the iPhone 11 and the battery has been further optimised in the 11 Pro.