What is the difference between 401(k) plan and Retirement plan?Is this the same or different?

"Retirement plan" is a general term that could refer to a specific investment vehicle such as a 401k. 401k is a specific investment vehicle sanctioned by the federal government that allows employers to place employee wages into a mutual fund (or bond fund or individuals stocks) which then grows tax free until it is withdrawn in retirement. For more information see: 401(k) - Wikipedia, the free encyclopedia

There are a lot of good books out there to help you understand these issues. A great place to start is "Personal Finance for Dummies." I know the title is offputting, but the substance is great. I hope this helps.