Difference between lay out and schematic diagram in thermal power plant?

A schematic diagram will show the connections required for the process concerned, which might be an electrical process or a pipework system. Such a diagram enables you to understand the connections without bothering with the physical layout of the system. In contrast a layout diagram will show the physical routes of the wiring or pipework. This type of diagram is used by the fitters who are fixing the hardware of the system, whereas the schematic will be evolved by the designers originally, to prove that all the connections required have been included. The layout diagram will be deduced from the schematic.