There are basically two wall construction methods for -Vinyl Liner Pools:

1)    Galvanized steel wall

2)    Composite polymer wall

Most companies will usually build with one or the other specifically.  There are advantages and disadvantages to both methods. 

Here are the advantages of composite polymer:

• Very light weight easy installation for installer
• Most shapes can be made
• Available in 42” or 48” walls
• Mostly used with aluminum coping
• Only two foot over dig needed

Here are the disadvantages for polymer pools:

• Must use cap lock on long runs to lessen warping
• Can degrade over time when in the ground
• Can crack due to improper back filling
• Best to use only swim out steps and benches
• Must use more panels to create shapes
• Best to fill with water before back filling

Here are the advantages of galvanized steel walls

• Can build any shape and size
• Less panels are needed to create radiuses
• Extremely stronger that Polymer
• Three foot over dig- More Footer
• Adjustable turnbuckle braces – assures a straight plumb wall with or without water
• Custom steps and benches with the liner installed right over
• Can be back filled easily with-out water in pool
• Very easy to install Cantilever concrete edging
• Very easy to install Coping
• Common size panels 42” an 48”, but can be made to any height

Here are the disadvantages:

• Much heavier than polymer- harder to install than polymer
• Can have surface rust on walls 10 to 15 years after installation (very easily rectified grind off rust and apply rust oleum paint and cover with ¼" wall foam)

As you can see Galvanized Steel wall pools are quite superior to polymer pools.