Difference between SELECT .. INTO and INSERT.. SELECT

Hi All,

I am on SQL Server 2008 R2. I have a very basic question.

What is the difference between SELECT ... INTO command and INSERT ... SELECT command, when inserting data into a tamp table or even a normal table? Or what is the difference between them in general?

When should I use SELECT ... INTO and when should I use INSERT... SELECT ?

Please guide.

Thanks in advance