ISO 9001 is the most difficult of the three standards to be chosen for certification , because it includes all the the twently elements. This comprehensive certification is desired by manufacturing organization which design their own products. For ISO 9002 certification, two of those twenty elements are dropped viz. Design and servicing, so as to focus more on manufacturing. ISO 9002 applies to firms which provide goods and / or services as per the design or specifications given by the customer. Many process industries used to pot for the ISO 9002 certification as they thought that their activities neither involve design nor servicing. However now many of these firms are seeing the parallels between R & D and design ( under the ISO ) and hence opting for the comprehensive ISO 9001 certification. The ISO 9003 standard drops most of manufacturing,, leaving only final testing and inspection. ISO 9003 certification is generally desired by organizations like the testing laboratories which inspect and test the supplied products. This ISO standard is the least comprehensive of the three.
It may be worth repeating that ISO 9000 series is a system standard and not a product quality standard. If a firm gets ISO 9000 certification. It does not automatically mean that the firms products / services are superior in quality to the other firm which has not opted for such certification. For instance for a ling time. Japanese forms producing excellent quality products have not bothered to obtain the ISO certification. This does not make their products and services inferior in quality.