The popular scientific opinion is that there used to be several domains, with some dying out completely, some never evolving much beyond their origins, and only two developing the vast majority of life on Earth.
But the differences between domains are very great.
Archaea were so different from bacteria that they were originally considered a kingdom, which is one level below domain. But even that is too close.
Archaea have no cell nucleus or any other membrane-bound organelles within their cells.
Imagine meeting someone who looked and somewhat acted like a human, but had no internal organs, and consumed liquid ammonia and used sunlight as food. That different.
You’ve met my ex?