My experience in Spain is that it is generally much cheaper and much quicker to travel by bus, except in certain particular cases. When the train is good, it's great. When it's bad, it's horrid.
The buses, on the other hand, are lovely, large, roomy, clean, with HUGE nice windows so you can sightsee. They run on wonderfully regular schedules to just about everywhere. I looked at the ALSA website and couldn't see that the buses go into Leon, and I'm not sure which "Barca" you speak of. But you can bet there is a good connection from point A to point B on the bus.
Regarding the train, here is something to be aware of:
When I was trying to get to the Peaceable Kingdom to visit Rebecca, I took a train from Santiago. I asked where to wait and a spot was pointed out. I asked what time the train arrived and was told.
2 minutes (literally) before my train was to arrive, another train stopped right in front of me. I figured it was mine and stepped on, only to find myself on my way to VIGO!!!!
It was a lovely trip ::laughing:: but totally opposite of where I wanted to go, Leon. This is apparently a common mistake and the rail service gave me a free ticket back to Reb's area.
Anyway.. please be aware that Spanish trains RUN ON TIME.. EXACTLY on time! Don't assume a train that is 2 minutes early is yours... there's probably another waiting right behind it.