If Ed 2 applies to your equipment, Ed 2.1 will as well and you will want to get the updated version. The nice thing about the new consolidated editions from IEC is that they show all the changes in red text. From quick glance, there are a fair number of changes. I am not an expert in this standard and don't have the time to do a detailed comparison but I can at least list out the clauses that have changed: 1.3.1, 2, 3, 3.1, 3.37 (new), 6.1.2 (complete rewrite), 6.3.2.2, 6.3.3.1, 6.3.3.2, 6.6.2.1, 6.8.1, 6.8.3, 6.8.4, 6.8.5, 6.10, 6.11.2.2, 6.12, A.2, A3.34, A3.37 (new), A5.2.1, A6.1.2, A6.2, A6.3.2.2, A.6.3.3.1, A6.3.3.3, A6.4.2, A6.8.1, A6.9, A6.11.2.2, A6.12, B.1, B.2, B.3, Table C.1, D.1. Hope this helps!