two worksheets overlaping data

OK I have two worksheets, I have one that has the updated product info. I have several hundred and don't want to key them by hand. They share the same product ID#.

What is the best way to over write the old info with the new?

Thank you,

can you not use a simple lookup function?

the data does not match. I might not understand how to use the lookup, becuase i thought it would only work if the product id's were in the same place on both work sheets.

Thanks

trying to use LOOKUP. if I want to compare Column A of sheet1 to column A of sheet 2 and if column A is the same for both sheets move data from Column D on sheet2 to Column D on sheet1.

Thanks