A system with heterogenous CPU topology is a system where the same ISA is used, but the cores themselves are different in speed. The setup is more similar to a symmetric multiprocessor. (Although such systems are technically asymmetric multiprocessors, the cores do not differ in roles or device access.)
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A common use of such topology is to provide better power efficiency in mobile SoCs. ARM big.LITTLE is the prototypical case, where faster high-power cores are combined with slower low-power cores. Apple Silicon has produced ARM cores with similar organization. Intel has also produced hybrid x86 cores codenamed Lakefield, although not without major limitations in instruction set support.
Alder Lake uses small and big cores.