What are the similarities and differences between traditional relay-contactor control and PLC control?

Are executed in accordance with the logical relationship! The difference is that in the control process of relay-contactor, there are too many cables and too much space, which makes it difficult to maintain and check the lines in the later stage; And PLC control is much more convenient, internal programs replace the logic control of most lines, and the volume of the power distribution cabinet will be greatly reduced! Later maintenance is also convenient!