Pearl's drum kit line
Pearl’s current line of drum kits includes eight series, ranging from entry level to professional grade, all of them use Pearl's heat compression SST system on the plies. In ascending order, they are:

Current Line
Rhythm Traveler – Traveler's kit. All drums in the kit feature shrunken depths. Package includes cymbals, throne, hardware, mesh heads and cymbal mutes. Rhythm Traveler drums are made with 6 plies (7.5 mm) of "Selected Hardwoods".
Forum – Most music stores will sell this kit with cymbals, throne, hardware and drumsticks at no extra charge. Forum drums are made with 6 plies (7.5 mm) of Poplar. Upgraded in January 2008 to FZ - now feature upgrades like ISS mounting. This is to replace the discontinued Export series.
Vision - Introduced in 2007, these drums are the replacement for the Export and Session drums. Vision drums originally came in 2 varieties: the VLX Lacquer finish drums, and the VSX Covered finish drums. The shell material is birch and basswood. 6 ply toms: 1 inner ply birch, 4 interior plies basswood, 1 outer ply birch. 8 ply floor toms and kick drums: 2 inner plies birch, 4 interior plies basswood, 2 outer plies birch. These drums are made in China, and also feature new lugs and come with the new 900 series hardware. These were meant to replace the Export drums. In 2008, Pearl introduced new varieties: the VBX with all birch shells and the VMX with all maple shells, and with the birch/basswood shells stopped producing the VLX, but have kept the VSX and also have a new line, the VX, which has Export-style wrapped finishes.
Masters Custom - Were introduced for 2007 and offer shells of 6-ply maple. These drums are the replacement for the entire Session line, and have a few differences from the Session kits: They feature Die Cast hoops, Masters-series lugs, and Remo drumheads. They are the same configuration as the Masters Premium MRP kits--but only come with 5 finishes and the only available hardware color is bright chrome. As a result the drums are not made up as "custom" stock, so they are warehoused in large quantities, and the time between order and delivery is much shorter.
Masters Premium – Released in January 2007, Masters Premium are 4 lines within this series consisting of, MMP, MRP, BRP, and BMP; they replace the Masters Series. MMP drums feature 4 plies(5.0 mm) of maple with maple reinforcement rings. MRP drums feature 6 plies(7.5 mm) of maple. BMP drums feature 4 plies(5.0 mm) of birch with reinforcement rings. BRP drums feature 6 plies (7.5 mm) of birch. All series offer choice in hardware color (black, gold, chrome--satin hardware has been discontinued for 2007). [1]
Reference - Released in January 2006. Pearl has blended wood types together for the toms, snare drums, and bass drums in order to create a unique and fully expressional sound for each individual drum. They are on high demand and are the highest quality that Pearl offers that are not totally custom. In 2008, 27 finishes were available.
Masterworks – Pearl's flagship model, hand made drums. Everything including the plies of wood (mahogany, maple, birch, carbon fiber/maple are some of the models), types of hardware material (chrome, 24k gold, black), and finish can be selected by the customer. Satin Chrome was also a hardware option, but has since been discontinued. For an added cost, Masterworks drums can be ordered with an exotic wood outer ply (such as tamo or bubinga) which enhances the finish.[2] delivery times can run six months.

Discontinued
Export - Pearl’s most popular series of drum kits, also the most popular set sold today. Export drums are made with 6 plies (7.5 mm) of Poplar, and come standard with Pearl's ISS suspension mounting system. As of January 2008, Pearl has discontinued these drums in favor of the new Vision series.
Export ECX - In January 2007 Pearl released the all-maple Export Custom ECX series drums. The ECX series feature 4 hand rubbed lacquer finishes and 100% maple shells. However, since January 2008 they have been replaced by the new Vision VMX.
Session - Session drums were made from 100% Maple or Birch shells depending on which the customer chose; both were 6-ply (7.5 mm). Session drums came standard with the Optimount suspension system and 2.3 mm Superhoops. Discontinued on January 2008.