Where do the terms overlap?
Both may display invented balances, accounts and transactions. Both can be used for screen content, interface concepts and fictional productions.
Neither is a real bank, and neither should process payments or verify funds.
Why does wording matter?
“Fake bank app” can sound like software intended to impersonate a financial institution. “LARP bank,” “bank simulator” or “fictional banking interface” more clearly suggests a creative or demonstrative purpose.
Clear product language helps users understand both the capability and the boundary.
What should you compare instead?
Compare editability, interaction, device support, local saves and the ability to use invented branding. Also check that the tool does not request real credentials or encourage the output to be used as proof.
These practical differences are more useful than the label on the product page.
Use the clearest description
For creative work, “fictional banking interface” communicates the purpose better than either slang term.