The Replace Mode capability allows you to right-click to replace the targeted block with the held block. This allows you to easily replace a large amount of blocks by holding the right-mouse button.
Additionally, when you replace a block, the newly placed block will inherit the properties of the old block.
A basic demonstration of Replace Mode can be found below
Type Replace can be toggled on through the Options Toolbox in the Alt Menu. Turning this on allows you to hold a base material block (eg. Spruce Planks) to replace stairs/slabs/walls/fences/etc. with their spruce variant
A demonstration of Type Replace can be found below