From our persepctive, metacreativity has distinct elements and core approaches that differ from conjuration magic in fundamental ways. You can absolutely draw parallels to some elements of metacreativity and conjuration, but they do not feel the same, especially when the player and DM embrace the dynamic differences. Mechanically, stylistically, and lore wise - Metacreativity is different. As it was added in the 3E era, our designs of the Metacreative powers tend to be evolved considerably from the books.
For example, you can steal aspects from targets nearby to augment your Astral Constructs if you have lingering powers impacting those nearby.
For example, when you make an astral construct, it comes from you. Not from the weave, or a god, or some other external source.