Apparently, according to the BBC, iTunes does not 'do' all podcasts plus the fact it's 'commercial'. Software like Juice 'finds' & indexes podcasts so you can sort out what you want to listen to, maybe as a stream rather that a download to save? I thought a lot was video, but it seems most is only audio and most of the BBC stuff I'd be interested in is streamed anyway.
I'll try the BBC listed ones, Doppler & Juice to see what's involved and learn a bit more.