How can a DB25 cable be wired for parallel and/or serial operation?

Unless I have "messed" up again (still?) the two are wired differently, or is that just with DB9 cables? Computer Network Accessories site advertises "6-Foot Molded DB25 Data cable for serial and parallel interface DB25 male to DB25 male, 25 conductors, shielded, molded. DB25M to DB25M, 6 ft, (1,8 m)".

Also what is the difference between a ("regular" as above) DB25 cable and a IEEE DB25 cable? My grand plan is to 1) become educated on Direct Computer Connections and to 2) hook my main 'chine to an older IBM PC 300GL via a parallel cable.

No, I doan have any answers, buts I gots alla da questions! Please alleviate my gross ignorance.