Difference between a bus and a wire
A wire can be a bus if it is a serial link carrying many individual pieces of information. More usually, a bus is regarded as a collection of wires that transport digital information from A to B. 64 bit processors (PCs etc.) have a 64 bit-wide bus between the CPU and their memory chips and possibly to other devices.

It doesn't have to be inside a computer of course - anything that is transmitting information from A to B will use some form of wire or collection of wires for achieving those aims.

What differentiates a wire as not being a bus is that it only carries one coherent "entity" such as power or a microphone signal or is connected to an on/off switch or a guitar or a speaker. A bus is usually digital.