Silas the Mariner said:This may sound silly, but what's the difference between the 3.5 SRD and the Core Rulebooks?
The SRD is the material other publishers may include in their works. The Core Rulebooks have examples that are not in the SRD, some rules, and some monsters that WotC considers too brand-specific to let go of.
Beholders and Mind Flayers are some of the monsters, for example, that are not in the SRD. They are too D&D-specific to have come from mythology or other published works, so WotC holds them back for trade reasons.
Character creation rules, like how much money characters should have at each level, are not in the SRD -- getting them is part of the added value of owning the actual books, and they are not rules that are needed for writing sourcebooks or adventures.