Charter ITC / Bitstream ?

I was looking for the Charter font from Matthew Carter and discovered that there are multiple versions.
I wonder if someone can tell me what are the differences between the 3 listed here (in terms of design, not concerning the rights to sell) :

ITC Charter (Linotype) (ITC Charter Regular - $35)
ITC Charter (ITC) (Charter Regular - $29)
Charter BT (Bitstream) (Charter Regular - $24.75)

Thanks for your help