Chorus field: Choose a classic stereo chorus effect, an ensemble effect, or disable the effects processor.
Off disables the built-in chorus circuit.
C1 is a typical chorus effect.
C2 is a variation of C1 and is characterized by a stronger modulation.
Ens(emble) uses a more complex modulation routing, creating a fuller and richer sound.
Midi Mode pop-up menu (Extended Parameters area): Determine how ES1 responds to MIDI controllers. Choose either Off or Full Remote.
Download the guides:
Logic Pro User Guide: PDF