Ocean breaks down the two core track types in Logic Pro before you build anything: MIDI and audio. Knowing the difference shapes how you record, edit, and produce every part of a song.
An audio track holds the actual sound, a recorded waveform you'll see as those wiggly lines. It only takes audio effects, and it's what you get from recording a guitar, vocal, or synth directly into Logic.
A MIDI track holds no sound at all. It's performance data, notes, velocities, timing, that gets sent to an instrument like a VST to generate sound.
That's what makes MIDI so flexible: you can rewrite notes, adjust velocity, and shift timing after the fact, something a recorded audio clip won't let you do.