There were still various 'hard' fixed function components in GPUs which would cause that kind of visual difference back in the day. Technically this does sort

There were still various 'hard' fixed function components in GPUs which would cause that kind of visual difference back in the day. Technically this does sort of still happen these days (eg the period of time when NVIDIA cards had ray tracing support but AMD cards did not, the quality of the video encoder, or nowadays with the various super-resolution methods used by each vendor), in which case those do tend to get treated separately in third-party benchmarks since not everyone really cares for the quality of those.