Cocos2dx: Difference between schedule and scheduleUpdate

This is the generic schedule:

//In GameScene.cpp

this->schedule(schedule_selector(GameScene::Update));

void GameScene::Update(float dt){

}

//In GameScene.h

class GameScene : public cocos2d::Layer

{

public:

    static cocos2d::Scene* createScene();

    virtual bool init();

    CREATE_FUNC(GameScene);

    

private:

    void Update(float dt);

};

This is scheduleUpdate:

//In GameScene.cpp

this->scheduleUpdate();

void GameScene::update(float dt){

}

//In GameScene.h

class GameScene : public cocos2d::Layer

{

public:

    static cocos2d::Scene* createScene();

    virtual bool init();

    CREATE_FUNC(GameScene);

    

private:

    void update(float dt);

};

ScheduleUpdate requires lowercase update.