Can anyone tell me what is the differences between the following standards?
1. Harmonized standard such as EN 980:2008
2. BS EN, DIN EN, etc....
3. ISO standards
An ISO or IEC standard is a INTERNATIONAL standard, published by an international SDO - standard development organization, meaning it´s generally recognized by the members bodies of ISO and IEC as the standard on the subject.
Standards are by default voluntary. Countries or regions (case of the EU), when they want to use standards in their regulations, have to call them in the regulation to make it an option or mandatory or whatever.
Due to a lot of reasons, countries or regions usually cannot directly use an international standard...they have to use a country or region specific version of the standard. These are developed by SDOs from countries or regions.
In the case of the EU, the SDOs are CEN or CENELEC (the EU ISO and IEC) which publishes EN standards (European Norms).
Harmonized standards are related to the directives in place on the EU. Basically, directives gives essential, general requirements, and harmonized standards provide more detailed requirements. Please note that, although harmonized standards are considered the "gold standard" on the subject (state of the art) they are are still voluntary - the manufacturer of the device can use any technical solution thet they see fit. The problem here is that compliance with harmonized standards gives what the directives call "presumption of conformity" with the related essential requirements. Oher standards or other solutions do not give this. So if not using an harmonized standard, you will need to justiry (in your risk management file) that the level of safety your product has is the nsame as if using a harmonized standard.
Finally, due to a lot of other reasons (mainly new approach directives and the global approach framework), countries in the EU have to have their own version of harmonized standards, or have to accept the general EU standard as a national standard. That´s why we have BS EN (british implementation of the EU standard), DIN EN (german implementation of the EU standard) and etc.