2
Been asked and answered plenty of times, there's even a
FAQ about it, but here we go again:
What is e-xoops? A fork of an earlier XOOPS version going in a different direction
How does it differ to XOOPS? Main difference is that XOOPS uses the Smarty template engine. There are probably more differences as it has been years since the fork.
XOOPS and e-xoops modules are not interchangeable
Whether one is better than the other depends on what you are going to use it for and what feels best for you
Why asking the same question twice? It is possible to port a module from one platform to the other, since both are programmed in PHP and basically, if you can do something in PHP, you can do it in (e-)xoops - how much work it is depends on the module's implementation.