The reality we perceive, our reality, isn't the one that our body exists in, external reality. This lemur refers to our reality as simply reality, but that's often not what we mean when we say the word.

When we say ideas "aren't based in reality" or when we talk about "snapping back to reality," we're referring to external reality. We always exist in our reality, but that reality is only an approximation of external reality. Snapping "back to reality" means realigning our reality to more closely match external reality.

In this sense, the lemur is mostly correct in saying that imagined realities are similarly real to our reality's approximation of external reality. Both are constructed by our mind. However, we almost always know the difference for most things that pass through our reality. Even people who struggle the most to figure out which perceptions come from external reality(think people with schizophrenia) can intentionally imagine things they recognize don't come from perception.

We distinguish current perception from memories and imagination, so I disagree that those things are equally fictional in our reality. They're equally constructed and we can be wrong about how we categorize things, but we do make a distinction. Fiction just isn't a useful word to describe all mental constructions or stories. It specifies when the story isn't based in external reality, not that it's a story.