@luispang,
1.Can i active crosshair axisX on each chart at same time?
Please take a look at this jsfiddle to Sync crosshair across multiple charts.
2.Can i get the value of different between axis X two point ?
Do you mean to calculate the difference by selecting the two dataPoints? You can select dataPoints on click as shown in this jsfiddle.
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Indranil Deo,
Team CanvasJS