Sankey Chart
Sankey chart represents nodes connected by lines/arrows and is used to visually show flows of any kind going from one node to another. The width of each line is pictured based on the flow quantity.
Sankey Diagram
A Sankey diagram visualizes flows (of any kind) and their quantities in proportion to one another. It represents nodes connected with one another by lines or arrows (the bigger the quantity, the wider the line). Sankey Diagrams are widely used in science, especially in physics.