Is an invitation card considered a general or a private invitation?

Responding to an invitation card is obligatory if it is sent specifically to the invitee, or if their name is on it for a wedding feast, provided there is no objectionable element (munkar) in it. If there is an objectionable element, and one can prevent it, then attendance is obligatory; otherwise, it is not permissible. As for cards distributed generally, responding to them is not obligatory unless it is known that the sender desires the invitee's presence due to kinship or friendship.