I am not sure what you mean here....
"Glass board vs Epoxy / production board" ???
There are polyester boards - which is (fibre)glass glued with polyester.
There are epoxy boards - which is (fibre)glass glued with epoxy.
both types above, are the typically custom handshaped and often have wood stringers or maybe carbon reinforcements or similar.
Production boards can be like above - just not polyester as it is very inferior in strength and durability, when applied to fibreglass, so not really used....
For custom shapers, the polyester has advantages as it has been used for years, before epoxy came - and polyester cost almost nothing - very cheap, and it cures quite fast so easy to work with when handmade. (I wont go into the flex discussion here...)
And when a board is "dead" - it is quite easy to make a new one.
But today many shapers use epoxy because of its physical advantages, so boards can be made lighter with the same strength - and way more durable, no heeldents, and it will not get cracks like polyester do very easy.
Then there are many production boards with different technologies involved, other core materials and outer protection layers etc etc - they can be very complex.
Epoxy are used in these boards, but outer layer can be a different type.
Most often polyester or epoxy are named "resin", like "epoxy resin", in the English language.
And when talking about fibreglass work, one says "laminating" - which means that several layers of wowen fibreglass or carbonfibre, and core material are wetted and glued together with epoxy or polyester, to form the surfboard with its strong and dynamic shell.
Would just explain these basics for readers, as it can be difficult to know if one has never worked with these things.
All boards are "glass" boards, just different glue (resin), either epoxy or the polyester.
And now I am curious, if your question is ?
Why do almost all comp riders use custom boards instead of production boards ?
Why do some comp riders use polyester custom boards, and others epoxy custom boards ?