They were basically the follow-ups to their biggest records. Both managed to be successful, although they didn't live up to the success of their previous records.
They're about even. PRISM had bigger singles and both Roar and Dark Horse are more remembered than any of BTW's singles. BTW sold more albums and the era itself (imagery, performances etc.) is more remembered than PRISM.
Had the BTWB not been canceled, it would have been a second +200M grossing tour for Gaga. The gross that would have been added to BTWB was estimated around $25M