Screen Print "REPLICA": These are sized like normal shirts M, L, XL, XXL. They have flat cuffs (no spandex), screen printed numbers and Bolts, and a diamond weave material. They retail for $74.99, but can be had for much less if you shop around (eBAY, etc). There is actually another screen print that retails for $49.99. It has a smaller, incomplete Bolt on the shoulder. Not very sexy.
Embroidered "REPLICA": These cheap jerseys currently known as PREMIERE or EQT. These jerseys are a bit fancier, retailing for $109 -- the "cheap mans" alternative to the AUTHENTIC.
AUTHENTIC: These are supposed to be the same thing worn by the players on the field. They have tapered sleeves that lead into spandex/elastic cuffs. They size them 48, 50, 52, 54, etc. They run big because they are built for use with football pads. These run $249.99 and up. Very expensive.