Differences among Chart Viewer, Chart web part and Excel Services

Chart Viewer	Chart web part	Excel Services
1)Simple web part that allows you to chart data from a SharePoint list	1)The chart web part is more general purpose web part that provides wizard based interface	1)Excel Services is the ultimate tool, because it is Excel rendered through SharePoint
2)This doesn’t allow for complex scenarios, formulas	2)Can connect to more data sources, such as the business connectivity services, lists, web part connections or even Excel Services	2)It has the most functionality, including spread sheets, formulas, charts and data connectivity
		3)The only downside of Excel Services is that it can’t connect to SharePoint data, so for charting data in SharePoint, you must use one of the other web parts