The 630 is big.LITTLE, two discrete sets of cores, they're just all A53's. Remember, the 650 spec sheet doesn't indicate it's big.LITTLE, either, it just denotes two obviously separate groups - 2x A72 + 4x A53.

"The Snapdragon 630 SoC uses a familiar octa-core Cortex-A53 CPU configuration. Unlike the Snapdragon 625/626 that it replaces, the Snapdragon 630 has a more distinct big.LITTLE arrangement with four A53s running at up to 2.2GHz (the same as the S626) sharing a 1MB L2 cache and four more A53s only reaching up to 1.8GHz and sharing a smaller 512KB L2 cache. While there should not be much difference in CPU performance and power compared to the Snapdragon 626, the Snapdragon 630’s Adreno 508 GPU performs 30% better on average than the S626’s Adreno 506 GPU. It also supports Vulkan and all of the latest 3D graphics APIs at resolutions up to 1920x1200. The Hexagon 642 DSP still supports Qualcomm’s Snapdragon Neural Processing Engine SDK for machine learning and TensorFlow, but does not share the Hexagon Vector eXtensions (HVX) microarchitecture of the more powerful Hexagon 680 and 682 DSPs."


That said though, the A72 cores on my Xperia X rarely ever cycle up under most load conditions and use cases. That indicates that, more often than not, the A53's are doing the bulk of the heavy lifting.

The A53's on the Xperia X are the same clock as the JP1. The Xperia X just has double the cores, much wider bus, much faster RAM.

The 630 is the same comparison. Yeah, you won't notice it just browsing, but you will notice the reduced power consumption, newer technologies (like Vulkan support in the 630), bigger battery and reduced heat. That's the point. I'm not saying it'll be like going from an AMD Duron to a Threadripper. I'm saying the power consumption reduction granted by the newer fab, the newer technology potential (faster eMMC, etc.) makes it attractive.

snapdragon 400 = 533MHz RAM
snapdragon 650 = 933MHz RAM, big.LITTLE
snapdragon 630 = 1333MHz RAM, big.LITTLE, hugely better GPU and better LTE modem, 14nm fab

I mean, I get it, on paper it looks like the same tech. It isn't. There are many more factors than just A53 cores.

Edit: some synthetics:

geekbench 4.1/4.2, 64-bit multicore:

snapdragon 650: 2869
snapdragon 630: 4170


kraken 1.1:

snapdragon 650: 3555
snapdragon 630: 9584