Is there any obvious difference in the appearance of the three switches of access, convergence and core?

Access switches are usually located at the edge of the network and are used to connect user equipment such as computers, printers, etc. They usually have some basic ports and functions, such as Ethernet ports, fiber optic ports, etc.

Convergence switches are usually located between the access switch and the core switch and are used to converge and forward traffic on the access switch to the core switch. They typically have higher port density and performance to support more access devices and higher traffic.

Core switches are usually located in the center of the network and are used to connect aggregation switches and other core devices. They typically have very high port density and performance to support a large number of access devices and data transmission.