In SCORM 1.2 the standard was write-only. This has always been an odd choice (because should I want to read what I wrote, I can’t). SCORM 2004 made an adjustment to this and went for the read-write model. The new model allows for interactions and can be helpful for reporting. On top of that, it allows you to check older interactions, see results and create a plan based on that.
One issue that was cause for a lot of negative feedback on SCORM 1.2 was the fact that it had only one status of the lesson: “Lesson_Status”. This could be completed, incomplete, failed, passed, browsed, or not attempted. For most this was enough, but others wanted to see more. For example, a learner actually fully completed a course but did not pass all the questions. In order to get multiple options available to the author, SCORM 2004 came up with the solution to split the lesson_status into completed/incomplete (completion_status) and passed/failed (success_status).
When first implemented, no one thought it would be possible and a lot of LMS did not support the option. The basics are simple. Sequencing allowed authors to add rules that defined the order in which content would be accessed by learners. It set up specific paths that could be adjusted per learner and allowed them to save results mid-course and continue at a later point in time.
So what do I need?
If your main goal is to just have a report on learners results, both options will suffice. The core of the reporting elements is the same. This changes if you are looking for more in-depth options like complex navigation and sequencing, you will have to go with SCORM 2004. If that is the case, make sure both your authoring environment and your LMS are SCORM-compliant. If you are only after the learners’ results, SCORM 1.2 will be all you need.