Can we assign same fields to different page layouts. How can we achieve this requirement. I have created few fields and assigned one page layout ( Account Lead), Now i want to assign the same fields to a different page layout ( Supply account). Please help me with this requirement.
In general, an option one always has is to "clone" an existing page layout and save it with a new name. You can then edit it to remove or add any fields you wish.
In the particular situation that you're describing, Supply Accounts would seem to have a different Record Type. You can create a unique Page Layout for displaying objects with that Record Type. That would easily be done when you specify a unique Record Type. You may want to look at creating Object Specific Actions which would help facilitate that. They're well covered in the Force.com Fundamentals as well as in the Salesforce Help. Other references that may be useful to you would be the Force.com Workbook, Tips and Hints for Record Types and the VisualForce Workbook.