Overview
CENELEC is the European body responsible for electrotechnical standards. It is the reason an international electrotechnical standard usually reappears across Europe as an EN, the European Norm prefix you see on the standards you cite. It is one of three recognised European standards organisations and covers electrotechnical work, while CEN handles general standards and ETSI handles telecommunications.
A large share of CENELEC's output starts at the IEC. When an IEC standard is adopted at European level it becomes an EN, often as an EN IEC number that keeps the original technical content. From there each country issues its own edition, which is how the same standard ends up labelled by national bodies such as DIN, with a VDE filing number in Germany.
Tracing a standard
A single document can carry several prefixes as it moves down the chain. EN IEC 63000 shows the pattern, starting as an IEC standard, adopted by CENELEC as a European Norm, then issued nationally. The technical content stays the same across the levels, and the prefixes just record which body has adopted it.
Note: general educational information, not legal advice. Check the official source before relying on it.