Update Sheet 1 with data from Sheet2

I have data on Sheet1 and data on Sheet2... both sheets contain the same records. On Sheet2 I have date stamp. Are there any fucntions where I say if the date stamp for that LastName field is different then update Sheet1 with the new data from sheet2?

Why not just link the cells with a formula? So when the workbook
is opened/calculated the second sheet will be updated with the
first sheets data or such. Add this formula to sheet1!A1 and it will
populate sheet1!A1 with Sheet2!A1

Code:

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=CELL("contents",Sheet2!A1)

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There are three fields on Sheet1 : LastName FirstName City
Sheet2 contains the same fields. Only difference is if the City is different on Sheet2 then replace the records where the LastName and FirstName are the same replacing the city withe the new city...