I have a great confusion about the terms "Model" and "Architecture". Is the TCP/IP is a model or architecture?. If it is model then what is architecture? What does the both terms refers to.
Network Architecture explain the responsibility of each network device based on its location down into 3 locations (Backbone , distribution , edge/access) and describe the responsibility of each tier.
The network architecture is the design of the network. What kind of backbone is used, what devices connect to the network and how are they laid out. Think of it as the blueprint for the network. Just like a blueprint of a house shows where the walls, electrical outlets, plumbing and doors are, network architecture shows the servers, network devices, end user computers, firewalls and how they are connected.
Meanwhile, a network model is a conceptual "drawing" of a network. Like the graphic from @Gadeliow, a network model explains how data passes along the network. From the originator to the destination how does the data travel and how is it addressed. Think of it as the post office concept for a network. You have the basics of what you want to send (say data to a database) and the model makes sure you have the right addresses, puts it in an "envelope" and sends your packet(s) over the network to their destination. If something gets lost, the model can use the header "address" to get that packet to it's destination.