Is a severance check from a company that you've retired from the same as an IRA payment?

I retired from SBC 3 years ago. I received a severance check to leave the company. I moved it into a money market. I was told at that time I was allowed to take out up to 30,000 as income and not be penalized on my taxes. When I got my taxes done the money I did take out was treated like it was in and IRA account. What is the difference in the two accounts.