Sub test()
Dim Ok As Boolean
With Sheets("Suivi des comptes")
.Range("C2:C1500").Interior.ColorIndex = xlColorIndexNone
Ok = WorksheetFunction.VLookup(.Range("C2").Value, Sheets("Noms produits").Range("f2:k50"), 4, False) > _
WorksheetFunction.VLookup(.Range("C2").Value, Sheets("Noms produits").Range("f2:k50"), 5, False)
If Ok Then .Range("C2:C1500").Interior.Color = RGB(255, 0, 0)
End With
End Sub