i honestly have no idea what you mean by operating architecture.

i used unix long before linux existed. the use of the term "unix-like" to describe linux resulted in legal battles and even today use of this term is discouraged by the custodian of the unix trademark.

some linux-based distributions don't have a posix-like environment so do not resemble unix at all. for example, the single most popular linux distribution is called android and is designed to be incompatible with a posix environment from libc on up.

Linux and Android, together at last - CNET