Difference 01
Start simple — just the melody
One line, single notes, low on the neck. No barre chords, no strumming pattern to drill first. It is the line people actually hum, and you can have it tonight.
Difference 02
Play in time with your piano buddy
A piano plays the chords, the bass and the beat while you play the line on top. It waits at 60% speed and keeps perfect time at any of them, so you are playing WITH something from the first run.