Podcasts are quickly becoming a substitute for traditional radio, but both media outlets are somewhat different
You could call podcasts and radio distant cousins; it's almost impossible to ignore the similarities. Both are media outlets that have audio and voice at their core (although - for a brief period of time - video podcasts were also a thing, before YouTube killed them). It's also easy to see that both are not exactly the same.
A radio show can be turned into a podcast, split into small pieces to listen to on demand. And a podcast can easily be broadcast on a radio station, providing it has enough quality. But something, or several things, sets them apart - both outlets have different constraints which end up affecting the final product.
1. Let's talk about anything
A radio station only has 24 hours to broadcast its programs and its goal is to maximize those hours by reaching the most diverse audience possible. Over the years, that has molded a certain kind of program (talk shows, news, music) that resonate with a wide audience.
Podcasts, on the other hand, do not have these limits and can enjoy a varying audience. This has allowed podcasts to focus on very niche topics that don't belong on traditional radio because they only attract a smaller portion of the audience.
The formulas that can be used on a podcast are also more varied. Genres that you almost never hear of on the radio anymore, such as fiction, can work in podcasts. Narrative and episodic formats, with a strong storytelling component, also find this medium has the ideal conditions to thrive.
2. Free from the tyranny of the clock
We have mentioned that the radio has only 24 hours, and that has also ends up affecting the way broadcasters produce the content. The tyranny of the clock is relentless and the shows need a certain rhythm because they start and end at very specific times.
Free from these constraints, podcasters can talk without a time limit. Even podcasts that have self imposed running times can run overtime on certain episodes. This makes the tone of the shows more natural and less formulaic.
3. Radio is for now, a podcast is forever
Although it is possible to make a live podcast, radio is still a much more suitable medium for such broadcasts; a live recording shapes the transmission in a very particular way.
The podcast, due to its form of distribution, can be discovered years after its original publication. That gives shows that do not dive into current affairs a very long shelf life, and eventually accumulate many downloads and reach a much wider audience.