The main difference of the Convention and the Orgalime S 2012 is that Orgalime S 2012 share the liability for delay and defects while the Convention find both to be a breach of contract following the same rules.
The other difference is that Orgalime S 2012 refers to Incoterms 2010. Many articles in the Convention are dealing with passing of risk.
A third main difference is dispute and applicable law.
The general conditions conclude the main conditions which ordinary happen but do not consider rare occurrences. The Orgalime S 2012 also apply for mechanical, electrical and electronic products while the Convention apply for any products.
Edition 2
I have changed my mind in some cases when CISG can be supplement to Orgalime S 2012. I have also made some clarifications and corrected some faults.
Ulf Contman