Difference between Digium TDM800 and AEX800


i simply dont understand the difference between these two Digium cards.
As far as i understand both cards support analog ports.

What i want to do is to feed 6 analog lines from an existing Nortel telefon system into an asterisk installation to give the six members of the it-team the power of VoIP.
Now i’m in the need of an PCI-Card (FXO) but i dont know which one of the two is better/right.
I think it should be the TDM800 with two X400M quad FXO modules, but i am not shure.
Could anyone please enlighten me here?


from the digium website with the most important part in bold by me:

The Wildcard TDM800P is a half-length PCI 2.2-compliant, 8 port card for connecting analog telephones and analog POTS lines through a PC.

The AEX800 is a half-length PCI-Express 1.0-compliant, 8 port analog interface card.

Which one you need depends on what the server you have\get has for ports.