What is a workbook ?
Actually an Excel workbook is a file that contains one or more worksheets.
When you open ms-excel in your PC then a workbook generates itself, when a workbook a generated it has three worksheets by default. (sheet 1, sheet 2 and sheet 3) you can rename a worksheet according to you.You can also add or remove worksheets according to your need.
What is a worksheet ?
An excel worksheet is platform where you can enter your data and information or records, an excel worksheet is a spreadsheet which contains much more columns and rows , that you can use to organize various kinds of related information.