Podcasting is no longer the domain of amateurs and the tech savvy. Talk radio is a professional business and the talent from that industry are beginning to start their own podcasts, and sometimes totally leaving FM/AM/satelitte radio behind.
In addition to pro radio hosts, nearly every comedian is also starting their own podcasts. Bill Burr runs one of the best. Hollywood is also adopting podcasts. Kevin Pollack runs a super popular show and is getting big interviews guests such as celebrities like Tom Hanks.
Podcasting is merging with the traditional entertainment industry and branching out from purely simple niche topics. Advertising is paying a lot of attention to podcasting. I heard one radio host gets paid $2 million/yr and he's not even the top podcast on iTunes.
So the difference is it's becoming a general, mainstream entertainment platform.