Unlocked? Storm vs. Bold

Brand new to BB. Already addicted. I bought my Bold 3 weeks ago and still have a week left with option for full refund. My dealer had told me AT&T couldn't sell the Storm because it was exclusive to Verizon. BUT, on this forum I see people DO have the Storm AND AT&T and they say they're "unlocked." Two questions: 1) What does unlocked mean? Does that mean I can still have the Storm with AT&T. 2) Do you prefer the Bold or the Storm?

Well unlocked means it can be used in any gsm carrier..If you go with the storm your taking away ( 3g,Wifi,Insurance tru at&t) and your getting ( ALot a headaches with the Storm)..I had the storm and made the switch to the Bold .Neva looked back..The storm still needs alot of upgrades ...

Thanks jsanta11! Big help.