Acting

i do both, and imo, acting is way harder. it's way more fun though

Singing, no doubt.

Acting.
You're convincing people you're a completely different person, seeing life differently, a different personality, style.
Must be difficult.

Acting

Singing, by far!!!

Without the assistance of a track almost everyone except for a very very very small few are able to sing completely in tune to the arbitrary 440hz scaling.

Mariah, Whitney, Beyoncé and some Opera singers are able to do that.

They are able to tell if an instrument being played is flat or sharp without a reference. (It's simply amazing)

This is what Bey meant went she said the DC girl couldn't sing, most people don't understand though.

To answer the question, acting is more difficult.

But from poll options, I'd choose becoming famous in reality tv show. Not everyone can be famous