The WRX is available in base, Premium, and Limited trims, offering progressive upgrades to upholstery, electronics features, and more. The STI is available in either standard or Limited trim, with its base spec higher than the base WRX's.
Some of the available options include leather seats and upholstery; a moonroof; touch-screen navigation with satellite radio; and more. Standard equipment is decent, with Bluetooth, a solid stereo, and auxiliary iPod/USB connectors.
Given the WRX's low base price, that may be the most attractive features: how Subaru has packaged so much performance, practicality, and convenience into such a small number. The WRX STI is considerably more expensive, but at the same time, outperforms nearly anything in its price range--while offering a competitive set of standard and optional features.