The numerical X axis of the chart allows setting the series items on the right location depending on their XValue property. This is especially important when the data does not come at regular basis and the chart has a time axis. DateTime values should be converted to their OLE Automation equivalents using ToOADate().
RadChart.XAxis.Appearance.ValueFormat property provides means to format X axis labels. For the first chart is is set to ShortTime, for the second one - it is ShortDate.