百富21 Limited Release，請教各位前輩

小弟在此求教各位酒國前輩:
究竟"百富21"與"百富21 Limited Release"有何相異之處？
Balvenie 21 : finished in port casks
Limited Release: extra matured in port casks, 另外有說明是使用 30 year old Port pipes
小弟實在查找不到相關資料，僅在下列網站看到Limited Release版"似乎"比較便宜...真的嗎?
http://www.scotchwhiskyauctions.com/auctions/31_the-eighth-auction-ended-sunday-november-27/1419_balvenie-21-portwood/
http://www.scotchwhiskyauctions.com/auctions/61_the-30th-auction-runs-until-sunday-october-6th/22752_-balvenie-port-wood-21-year-old/
不知二者是否是同樣的製程、品嘗起來有何相異、價格是否有差異、LR版在哪可購得?
因為LR版已經被家人給乾了，小弟一滴未嘗....殘念......
望各位大大不吝指教，小弟拜謝!!