The E-cores are just rebranded Atom cores. The evolution of the Atom cores has been continuous in the series ... Silvermont, Airmont, Goldmont, Golmont Plus, T

The E-cores are just rebranded Atom cores. The evolution of the Atom cores has been continuous in the series ... Silvermont, Airmont, Goldmont, Golmont Plus, Tremont (also included as E-core inside Intel Lakefield), Gracemont (from Alder Lake/Raptor Lake/Alder Lake N/Amston Lake), Crestmont (from Meteor Lake/Sierra Forest), Skymont (Lunar Lake/Arrow Lake), Darkmont (Clearwater Forest). All the cores of this series have been designed in succession by the same team and the improvements between them have been incremental. These cores have always been intended as competitors for various Arm Cortex-A cores, e.g. Goldmont Plus for Cortex-A75, Tremont for Cortex-A76, Gracemont for Cortex-A78, and now Darkmont/Skymont for Neoverse V3/Cortex-X4. Before Tremont, these Atom cores were used only in homogeneous CPUs. In recent years only those sold for industrial applications have retained the brand "Atom". The most recent CPUs branded as "Atom" have been launched last year. For now, it does not matter whether one refers to any of these cores as "Atom" cores or as "E-cores", because either name refers unambiguously to the same cores. "Atom" seems preferable, because it is more clearly Intel-specific. One could refer as "efficient cores" to cores in CPUs made by others. The first E-cores were the Tremont cores of Intel Lakefield, which was launched in Q2 2020, which were paired with Ice Lake cores, and which had a performance much less than Skylake cores. Only the next generation of Atom cores a.k.a. E-cores, Gracemont, has reached performances comparable with Skylake. While Gracemont was first launched in Alder Lake, later it has become widely available in Atom-branded CPUs.