Less cache, much smaller OOO window, AVX-512. E-core is an area play so Intel can score some multi-thread benchmarketing wins on integer heavy code that don’t have larger memory/cache footprints, don’t require much speculative depth, and naturally have high amounts of ILP. They completely fall flat on plenty of workloads. And the way Intel runs them is absurd: 10+ watts per e-core just to eek out a MT win is pure absurdity.

Until Intel has a p-core that isn’t grossly obese, they have no option but to spam e-cores just to make powerpoint slides.