You're wrong about categories of analogy, but I don't blame you - analogies are a pretty slippery slopes. In particular, you're most likely conflating these because of the implementation detail - you write HTML, so writing music is an analogy. Not really - writing HTML is closer to performing music.

You can teach almost everyone to perform "Twinkle Twinkle Little Star" on piano or "Smoke on the Water" on guitar within 15 minutes, both of which are de facto "Hello world!" equivalents to many aspiring musicians.

EDIT: Removed attempt at drawing a HTML/music analogy which could be closer to truth. It is really fruitless endeavour, makes no sense.