Some boards support protocols and peripherals that others do not: the Arduino Uno has analog-in pins while the Pi does not, but the Pi has USB support while the Uno does not. Luckily, the Johnny-Five documentation, under Platform Support, tells you what is and isn't supported. The Uno is shown here as an example:

Now that you've got a glimpse at where you can continue your adventure within Johnny-Five, let's take a look at the even larger NodeBots world outside.