Difference between NAICS and SIC Codes

I tried to google this topic, read many links but still could not understand the difference between NAICS and SIC codes. Can someone make me understand.

Further can someone provide a an hierarchical list of these codes?

Which one of them is currently used in the USA?

Thanks in advance

Best Regards
Imran Bhatti

Try here: https://www.naics.com/what-is-the-di...and-sic-codes/

Links to the hierarchies at the bottom, I believe:

https://www.naics.com/business-lists...s-by-sic-code/

https://www.naics.com/business-lists...#countsByNAICS

Click on the links within to go further into the hierarchy.

Thanks for the useful links. one of them I already had.

Appreciated

How can I confirm which system is currently in practice?

No idea, sorry.

If I read it correctly: the amout of characers 4 vs. 6