Understanding the different types of dress shirt fabrics available is not a simple task because there are so many different characteristics to consider. Nonetheless, here are a few pointers.

OXFORD CLOTH
Oxford Cloth uses a heavy thread, has a rougher texture, and is fairly durable. It uses a symmetrical basket weave where one yarn may cross two yarns. It's origin is from sports, so it's the least dressy, and (in some circles) not considered appropriate for wear after 6pm.

TWILL, HERRINGBONE, HOUNDSTOOTH
These are considered the most durable fabrics, the hardest to "soil", and hardest to clean if "soiled". Technically they are all Twill fabrics, but depending how the weave is implemented, they will show a herringbone pattern, houndstooth pattern, or a simple diagonal texture or stripe.

PINPOINT
Pinpoint fabrics have the same weave as oxford, but uses a finer yarn and tighter weave making it a more formal fabric.

BROADCLOTH
Broadcloth fabrics (which are the same exact thing as Poplin, employ a tightly woven fabric with a very simple over-under weave and slight sheen, which makes it very dressy.

PIMA
Generally the same simple weave as broadcloth - but with long-staple (some would say superior) fibers. Because the fibers are longer, it can feel softer and be more absorbent. It also is often thicker than broadcloth or other, finer weaves. Generally less expensive than Egyptian or Sea Island cotton. To make things more confusing, it is also a trademark.

END-ON-END
Also known as end-and-end, end-to-end or fil-a-fil. This is a closely woven weave, similar to broadcloth (some fabrics are "broadcloth end-on-end"). It has alternating colored yarn and a white yarn creating a mini checkered effect with a smooth texture. It's often made with finer yarns than broadcloth and in those situations can be very dressy.

EGYPTIAN AND SEA-ISLAND
Generally considered the finest cotton in the world, this cotton uses especially long, strong and silky fibers. As a result it is soft, silky, and expensive.

THREAD COUNT
The other fabric parameter that is mentioned a lot is Thread Count. This is the number of threads per inch of fabric. It's not the most precise number, and (from my experience) is usually either "60s", "80s", "100s", "120s", "140s", or "160s". Generally higher thread count fabrics are smoother, more comfortable and more expensive. Some threads are made from one yarn and others are made from two or more. The number of yarns per thread is the fabric "ply". You'll often see a fabric referred to as "80s two-ply" or "100s two-ply". Two-ply fabrics are usually more comfortable and more expensive than single-ply fabrics.

COUNTRY OF ORIGIN
This is often hyped, but often misleading. While Italy and Switzerland are generally regarded as the source of the worlds finest fabrics, there are increasingly great quality fabrics produced all over the world. Historically we only sourced fabrics from Italy, however we've also begun to source some really cool stuff from Japan.