One is rendered in JavaScript, the other in Flash. Functionally, they are equivalent. Most choose one or the other based on the user's browser support. If mobile users will be using the chart, Flash is not usually available, and thus they won't see the chart. I have also seen situations where the JavaScript version doesn't render as expected in certain browser (most recently have seen issues with Chrome while using a zoom level).
More information about charts in Splunk, can be found at these locations:
Splunk 4.3.4 and earlier -> http://docs.splunk.com/Documentation/Splunk/4.3.4/Developer/CustomChartingConfig-Overview
Splunk 5.0 and later -> http://docs.splunk.com/Documentation/Splunk/5.0/Viz/CustomChartingConfig-Overview
JSCharts do not necessarily have all the same features of FlashCharts. Be sure to check the properties pages to see which features work with JSCharts.
@sdvorak_splunk
Is it possible to resize JSChart somee how at run time.
More info from the docs: http://docs.splunk.com/Documentation/Splunk/5.0/Viz/CustomChartingConfig-JSChart. In the Custom Chart Configuration Reference (linked above), each table has a column to indicate whether specific properties are supported in JSChart.
Agreed, there are properties available through Advanced XML that are not available in JSChart module. For advanced visualizations, the Flash version will be the most customizable. That said, the Flash version is the "legacy" version, and Splunk is working to bring JSChart to parity.
One is rendered in JavaScript, the other in Flash. Functionally, they are equivalent. Most choose one or the other based on the user's browser support. If mobile users will be using the chart, Flash is not usually available, and thus they won't see the chart. I have also seen situations where the JavaScript version doesn't render as expected in certain browser (most recently have seen issues with Chrome while using a zoom level).
JSChart also renders much faster and uses far less system resources than FlashChart's. This can be very evident if you have dashboards with many charts displayed on the same page, and particularly on systems & mobiles with low memory available for flash.