Released back in May 2018, CentOS Linux 7.5 is based on the Red Hat Enterprise Linux 7.5 operating system and supported 32-bit (i386), 64-bit (x86_64), ARM64 (AArch64), PowerPC 64-bit Little Endian (PPC64el), PowerPC 64-bit (PPC64), and ARMhf architectures.
However, the initial release only supported IBM POWER8 processors, but it’s now available for IBM POWER9 processors too. According to the announcement, the key difference between the CentOS Linux 7.5 releases for IBM POWER8 and IBM POWER9 processors is that the one for POWER8 processors uses the Linux 3.10.0 kernel series, while the one for POWER9 processors uses the more recent and long-term supported Linux 4.14.0 kernel series. Other than that, the rest of the system packages are identical.