Although they have similar visual appearances, Bus bars and terminal blocks serve very different purposes. The main difference between a bus bar and a terminal block is that a bus bar gathers multiple wires together for electrical distribution in a single circuit. By contrast, a terminal block has separate circuits where each incoming wire is paired with an outgoing wire.
A simple way to think about it is that a bus bar is a single circuit and a terminal block is multiple individual circuits. Visually, you can tell them apart by two distinct factors. First, a bus bar is a solid piece of uninterrupted metal. You can see when looking at a terminal block, that each section is independent of the others separated by a dividing wall. The second distinction is the studs commonly found on bus bars that are not present on terminal blocks. You can find all the parts you've seen here, and more, at pacergroup.net