GarageBand Instruments are actually less CPU and memory-intensive versions of equivalent Logic Pro instrument plug-ins. The GarageBand synthesizers use a cut-down version of the ES2. Similarly, organ sounds are generated by a feature-limited EVB3, and electric piano sounds are emulated by an instrument based on the EVP88. Other sounds, such as strings, brass, drum kits, and so on, make use of a simplified sample player that is based on the EXS24 mkII.
The interface of all GarageBand instruments is limited to a few key parameters, simplifying their use. The available parameters were carefully chosen to provide maximum impact and flexibility, making it easy and fast to create great sounds.