I was offered a new position by my current company where the job description has changed more than 50%, but they did not offer me a serverance package when I did. It accept it. It was a take or leave it situation. The employees that were not offered a position were given a package.

It is possible that you could have rejected the position and alleged constructive dismissal. However, now that you have accepted the new position, it is unlikely that you can allege constructive dismissal. To summarize, due to the fact that you accepted the new position, you are unlikely to be entitled to a severance package.