The difference here though is that the ARM1 uses a PLA to directly decode an ARM instructions into a small number of clocks worth of things to do (enables to ALU stages/etc), while the x86 decodes an instruction into the address of a bunch of microinstructions in a ROM which then get executed with a micro PC (including subroutine calls). Sure the x86 microinstructions also directly control enables to ALU stages/etc, but the difference is that they also include what are effectively opcodes in their own rights.

In short the ARFM has decode logic that makes a bunch of clocks worth of ALU controls directly, while the x86 has decode logic that makes an index into a ROM from where that information is read/generated