Using the same seed, you'll get the the same image with the same prompt. Either way, they're both partially a generalization of what those words represent.

> When anyone else, using the same prompt, gets the same image?

Though, to answer them, legal copyright is concerned with human creative effort. Choosing novel and interesting inputs for a final art piece is somewhat comparable to choosing a gradient when using photoshop. The legal copyright being enforceable will likely be on if the court determines enough creative effort went into creating the image.

In the following video a copyright lawyer on YouTube (Lawful Masses) covers the spectrum of fair use and copyright ownership. I think this video provides a insight into how a the legal system might also determine if someone owns copyright to AI generated art. They also recently covered AI generated art in another video, but I think the first video better explains how law isn't simple binary choices.