What is the difference between CellValues.InlineString and CellValues.String in OpenXML?

I am trying to write some code to generate an Excel spreadsheet and I am not sure what the difference between CellValues.InlineString and CellValues.String to insert text on the cells.

Shall I use this:

private void UpdateCellTextValue(Cell cell,string cellValue)
{
    InlineString inlineString = new InlineString();
    Text cellValueText = new Text { Text = cellValue };
    inlineString.AppendChild(cellValueText);

    cell.DataType = CellValues.InlineString;
    cell.AppendChild(inlineString); 
}

this

private void UpdateCellTextValue(Cell cell, string cellValue)
{
    cell.CellValue = new CellValue(cellValue);
    cell.DataType = new EnumValue<CellValues>(CellValues.String);
}

or just this (InsertSharedStringItem returns the Id of the newly inserted shared string item)

private void SetCellSharedTextValue(Cell cell,string cellValue)
{        
    int stringId = InsertSharedStringItem(cellValue);
    cell.CellValue = new CellValue(stringId.ToString());
    cell.DataType = new EnumValue<CellValues>(CellValues.SharedString);
}