Tier on tier shutters are the most versatile option, as you have two sets of shutters assembled on top of each other covering the full height of the window. This gives you the option to have the top set open whilst the bottom set are closed or vice versa; think of this style like stable doors. The top tier and bottom tier are completely separate and can be divided at any point in the window.
This style gives you the option to have the top louvre’s tilted open whilst the bottom closed flush to the window for privacy and to maximise the light.
Tier on tier shutters are much like Full Height Shutters with a midrail, however this style gives you more solid borders within your window. This may sometime’s decrease light entering the room however, can keep the room warmer as they act as insulation in winter and in summer you are able to open all panels top and bottom for maximum ventilation. Tier on tier are popular choice for common space windows which are in need of a lot of flexibility.