Piano teachers have opinions about this. Strong ones. The classical crowd says you need proper foundations. The pop crowd says learn what you love. Both are right. Both are wrong.
Here's the actual difference:
Classical piano emphasizes reading music precisely as written. Every note, every dynamic, every articulation matters. You're interpreting a composer's specific vision. Technique is formalized – there are "correct" ways to do things developed over centuries.
Pop piano is more flexible. Lead sheets give you chords and melody – you fill in the rest. There's more improvisation, more room for personal interpretation. Technique matters but there's less orthodoxy about exactly how you play.
What classical teaches well: reading complex notation, hand independence, precise technique, dynamic control, long-form pieces that develop over time. If you want to eventually play Chopin or Beethoven, you need classical training.
What pop teaches well: chord progressions, playing by ear, accompanying yourself or others while singing, improvisation, quick arrangement skills. If you want to play at parties or accompany vocalists, pop skills are essential.
My take: Learn what keeps you motivated at first. If classical pieces bore you, don't force them – you'll quit. If pop feels too simple, go classical. Enthusiasm matters more than optimal curriculum.
But eventually, learn both. The skills complement each other. Classical precision improves your pop playing. Pop flexibility and chord awareness helps with classical interpretation.
For beginners I'd suggest: Start with whatever you enjoy. After 6-12 months, deliberately add the other style. A diet of only one style creates blind spots.
For specific classical pieces that aren't boring, see my recommendations. For pop songs, easy songs to start with.