Tokøta from Mastering.com breaks down Logic's ES2 synth, showing how its three envelopes and two LFOs shape both a patch's character and its movement over time.
Envelope 1 controls amplitude, and its attack, decay, sustain, and release settings define the sound: fast attack and short release for plucks, long attack and release for swelling pads, short attack with medium decay for punchy bass.
LFO2 is the one to use for tempo-synced motion, like eighth-note vibrato on pitch or rhythmic cutoff sweeps. LFO1 is polyphonic and unsynced, so each note's modulation starts from a different point in its cycle.
Envelopes can modulate the same targets as LFOs, like cutoff or resonance, but fire only once per note instead of repeating, which is the core difference between the two modulation sources.