STM32F4 定时器控制ADC的采样率

STM32F4 定时器控制ADC的采样率以及定时器触发ADC有什么区别么？小弟打算利用TIM来控制ADC采样率，在配置过程中遇到如下

/* ADC1 regular channel 12 configuration ************************************/
ADC_InitStructure.ADC_Resolution = ADC_Resolution_12b;
ADC_InitStructure.ADC_ScanConvMode = ENABLE;
//ADC_InitStructure.ADC_ContinuousConvMode = ENABLE;//Á¬ÐøģʽÊÇʲô¿    
ADC_InitStructure.ADC_ContinuousConvMode=DISABLE;
ADC_InitStructure.ADC_ExternalTrigConvEdge = ADC_ExternalTrigConvEdge_Rising;
ADC_InitStructure.ADC_ExternalTrigConv = ADC_ExternalTrigConv_T2_TRGO;//_TRGO定时器触发？？？
// ADC_InitStructure.ADC_ExternalTrigConv = ADC_ExternalTrigConv_T2_CC2;//与上者有什么区别？
ADC_InitStructure.ADC_DataAlign = ADC_DataAlign_Right;
ADC_InitStructure.ADC_NbrOfConversion =10;
  ADC_Init(ADC1, &ADC_InitStructure);
    
//     /* Enable ADC1 DMA */
//  ADC_DMACmd(ADC1, ENABLE);