The QNetworkAccessManager class allows the application to send network requests and receive replies. QNetworkAccessManager class which holds the common configuration and settings for the requests it sends
The QTcpSocket class, part of the Qt framework, provides a TCP socket.
"Qnetworkaccessmanager is higher level than qhttp and qtcpsocket so they have abstracted away the sockets connection state"
from question "How to obtain QNetworkAccessManager's connection states?"