What is the difference of the following types of sheetpiles Z-type, U-type, flat web and Pan-type?

Z-type: The interlocks are situated as far away from the neutral axis as possible to facilitate good shear transfer and to enhance higher strength to weight ratio. This is the most common type of sheetpiles used in many countries.

Pan-type: Pan-type sheetpiles are smaller in size than most other sheetpiles. Owing to their smaller size, they are commonly used for resisting short and light loaded structures.

Flat web: The mechanism in resisting load differs from other types of sheetpiles. Flat web are usually installed in circles and the sheetpiles are held together by tensile strength of the interlock.

U-type: U-type sheetpiles perform in similar manner as Z-type sheetpiles. The major difference between them lies on the location of interlocks. For U-type sheetpiles, the interlocks are located at neutral axis which reduces the efficiency of the section. The properties of U-type shall be decreased owing to the problem of shear transmission.

This question is taken from book named – A Self Learning Manual – Mastering Different Fields of Civil Engineering Works (VC-Q-A-Method) by Vincent T. H. CHU.