When I set the column widths and height in an excel workbook and save it.
Then my co-worker opens it, why are the column widths different (sometimes
resulting in printing on two pages instead of the intended one page). How do
I correct this so both are the same.

Thanks,

If your co-worker is using a different printer, the allowable margins
may differ from the printer you use.

Where I work we have workbooks that print to one page on our network
laser printers but two pages on local inkjets.

You would need to adjust your column widths to work on your co-worker's
printer.