Qt에서 QThread와 QFuture의 차이는 뭔가요? (코드첨부)

#ifndef BACKGROUND_H
#define BACKGROUND_H
 
#include <QThread>
#include <QObject>
 
#include <QDebug>
 
class Background : public QThread
{
Q_OBJECT
public:
   Background(QObject* parent = 0):QThread(parent){}
protected:
   void run()
   {
 
	   double cardSoldier = 0;
	   for ( int heart = 1 ; heart < 20000 ; heart ++ )
	   {
		 for ( int spade = 1 ; spade < 20000 ; spade ++ )
		 {
			cardSoldier = cardSoldier + ( double(heart)  / double(spade) );
		 }
	   }
 
	qDebug() << (QString("Child function ran in thread: ")) << QThread::currentThreadId();
   }
};
 
class BackgroundConcurrent : public QObject
{
Q_OBJECT
public:
   BackgroundConcurrent(QObject* parent = 0):QObject(parent){}
public slots:
   void doWork() const
   {
 
	   double cardSoldier = 0;
	   for ( int heart = 1 ; heart < 20000 ; heart ++ )
	   {
		 for ( int spade = 1 ; spade < 20000 ; spade ++ )
		 {
			cardSoldier = cardSoldier + ( double(heart)  / double(spade) );
		 }
	   }
 
	qDebug() << (QString("Concurrent child function ran in thread: ")) << QThread::currentThreadId();
   }
};
 
class BackgroundTrigger : public QObject
{
Q_OBJECT
public:
   BackgroundTrigger(QObject* parent = 0):QObject(parent){}
   ~BackgroundTrigger()
   {
	  foreach(QObject* child, children())
	  {
		 QThread* childThread = qobject_cast<QThread*>(child);
		 if (childThread)
			childThread->wait();
	  }
   }
public slots:
   void triggerWorker()
   {
	  Background* child = new Background(this);
	  child->start();
   }
};
 
#endif // BACKGROUND_H

#include "Background.h"
 
#include <QtCore/QCoreApplication>
#include <QtConcurrentRun>
 
int main(int argc, char *argv[])
{
    QCoreApplication a(argc, argv);
 
	// Using QThread
	BackgroundTrigger childTrigger;
	qDebug() << (QString("Main function ran in thread: ")) << QThread::currentThreadId();
	// Call child
	childTrigger.triggerWorker();
	childTrigger.triggerWorker();
 
 
	// Using QtConcurrent
	BackgroundConcurrent cchild;
	QFuture<void> future1 = QtConcurrent::run(&cchild, &BackgroundConcurrent::doWork);
	QFuture<void> future2 = QtConcurrent::run(&cchild, &BackgroundConcurrent::doWork);
 
 
    return a.exec();
 
}