请教几种广播模式的分别

小弟刚接触蓝牙，还请大神解释一下这几种广播模式有什么具体的分别
typedef enum
{
    BLE_ADV_EVT_IDLE,                /**< Idle; no connectable advertising is ongoing.*/
    BLE_ADV_EVT_DIRECTED,            /**< Direct advertising mode has started. */
    BLE_ADV_EVT_DIRECTED_SLOW,       /**< Directed advertising (low duty cycle) has started. */
    BLE_ADV_EVT_FAST,                /**< Fast advertising mode has started. */
    BLE_ADV_EVT_SLOW,                /**< Slow advertising mode has started.*/
    BLE_ADV_EVT_FAST_WHITELIST,      /**< Fast advertising mode using the whitelist has started. */
    BLE_ADV_EVT_SLOW_WHITELIST,      /**< Slow advertising mode using the whitelist has started.*/
    BLE_ADV_EVT_WHITELIST_REQUEST,   /**< Request a whitelist from the main application. For whitelist advertising to work, the whitelist must be set when this event occurs. */
    BLE_ADV_EVT_PEER_ADDR_REQUEST    /**< Request a peer address from the main application. For directed advertising to work, the peer address must be set when this event occurs. */
} ble_adv_evt_t;
不胜感激！！！！