Black = 05' 4300 (with disc brakes...but im getting the one without) Red = 04' Hardrock SportBlue My reply.


FRAME: Alpha SL Aluminum High-strength A1 Premium Aluminum frame featuring forged dropouts with eyelets, reinforced disc mount, forged alloyThat A1 Premium Aluminum frame with the forged dropouts with eyelets, reinforced disc mount, forged alloy is much stronger than that Alpha SL Aluminum. Trek doesn't forge dropouts which is why the majority of their bikes are v brake only. Forged is stronger than Non forged.
FORK: RST Gila T5 w/preload adjust, 80mm RST Gilla T4, 100mm travel, preload adjust, Cr-Mo steerer, coil/MCU springBoth forks aren't the greatest, but the t4 is higher up on the RST foodchain.

WHEELS:
WHEELS: Shimano M495 disc hubs; WTB Speed Disc rims Joy-Tech, 32 hole, ground race double sealed loose ball w/ alloy QR; Alex double-wall rims with CNC braking surfaceWTB may make good tires and Saddles, but their rims downright stink. There have been more positive reviews with the Alex double-wall rims.

TIRES: Bontrager ACX, 26x2.2", 52/54 Specialized Enduro Sport 26"x2.0"The Bontrager ACX's wear out very quickly. Specialized Enduro Sports do to but nowhere near the rate that the bontragers will.

DRIVETRAIN:
SHIFTERS: Shimano EF29 Shimano AltusEF29 is basically depot store level. Altus isn't.
FRONT DERAILLEUR: Shimano C050 Shimano AceraC050 Depot store level. Acera is right above Depot store level.
REAR DERAILLEUR: Shimano Alivio Shimano AceraAlivio used to be had for a lbs level, but has sunk to Depot Store level. Acera can't be found in Depot Stores.
CRANKSET: SR 42/34/24 Truvativ ISO-Flow
CASSETTE: SRAM 850 11-32, 8 speed Shimano HG-50,Sram 850 is Depot store stuff again. HG50 is actually Acera level.
PEDALS: Alloy platform, clipless adaptable Dual sided, composite body, steel cage, toe clip compatibleThe only advantage the trek has but remember the pedals are usually the first thing to go so null point.

Also when comparing bikes like you were, compare 2004's with 2004's and compare 2005's with 2005's.