We have realised that a current development is still using legacy code, including ADODB version 4. I understand that there are quite a few differences between 4 and 5, but I can not find any information about these differences. Can anyone tell we where I might find details of the differences between the two versions? Thanks
ADOdb 4.x has not been maintained for nearly 10 years now (last release 4.990 goes back to 11 Jul 2008).
To the best of my knowledge (I only joined the ADOdb project much later, around 2013, and never actually used version 4.x), the main difference was about PHP 5.x compatibility; I believe that bug fixes and improvements were applied to both branches simultaneously for a while (as shown in the changelog).
I don't know of any documentation detailing the differences; feel free to browse the project's source code and compare the current version of the code with the legacy adodb4 branch branch.