Human Creations vs. AI Creations — What’s the Difference?

I came across the following tweets in the past few days that really show the sophistication of today’s AI technologies:

Some of our classmates have posted really interesting thoughts about how copyright law could apply in relation to AI, with many concluding that under the current state of copyright law, works that may otherwise be copyrightable if created by humans are not copyrightable if created by AI.

This leads me to wonder how one can make this distinction in practice. Given how polished AI-generated works are becoming, would we even be able to tell the difference between works created by AI versus by humans, and is this distinction between an AI creator and a human creator one that can hold up in the future as a key factor in determining whether a work is copyrightable?