Adele decided not to make her album 25 available for on-demand streaming via Spotify, Apple Music and related services, and went on to break all earthly sales records with a mega-debut of 3.4 million. She is on track for the second-biggest week of the year in her second week, with conservative estimates putting her in the 850-875k ballpark.

But correlation doesn’t necessarily imply causation, as the science nerds like to say. Would 25 have sold as much if it had been streamable in full upon release, or would the ability to listen without buying have cannibalized sales? We’ll never know for sure.

For those who think this is an open-and-shut case—they can’t stream it, so they gotta buy it—it’s illuminating to turn to the second-biggest sales story of the moment: Justin Bieber’s Purpose, a remarkable comeback story that continues in the wake of his chart-topping bow.

Not only does Purpose sit at #3 and #4 (in deluxe and standard editions) on the iTunes chart, but he has singles at #2, #3 and #11. Meanwhile, Purpose and its various hits have smashed all manner of streaming records on Spotify and elsewhere.

Shouldn’t all that streaming, which has helped propel Bieber to colossal numbers on the HITS SPS chart, have cut into his sales? Yet he sells on, and vigorously.

Streaming is but one instance in which these two hugely successful projects diverge. Adele embraces classic pop sensibilities; Bieber’s music is utterly of the moment, with EDM styles dominating. Adele has largely eschewed social media; Bieber (with his team, overseen by the tactically brilliant Scooter Braun) has worked it masterfully. Adele has refused to do any commercial endorsements; Bieber has a boatload of brand partners.

Yet both continue to perform magnificently in the marketplace.

These two resounding successes underline at least one truth: There is no one-size-fits-all rule for making, marketing or delivering a record. And whether you stream or don’t, tweet or don’t, hawk product tie-ins or don’t is entirely moot if you don’t have the goods. Adele and Bieber both delivered music that their audiences wanted. How those listeners found out about it, or the platforms through which it could be accessed, mattered far less than the music itself.