5/8” and 16mm tools are theoretically interchangeable. 16mm is technically 6.299, where 5/8” is .625. So the difference in diameter is only .049.
So if you see a tool labeled as 5/8”, it will definitely fit in any hole made for a 16mm tool. However, this is where things get tricky – there’s absolutely no industry standard for fabrication tables with 16mm holes! I wrote an article addressing this topic here.