‏What is the difference between diario and periódico ?
Feel free to just provide example sentences.

See a translation

Referring to a newspaper they're the same, or at least, we use both as synonyms.

"- Qué estás haciendo?
Estoy leyendo el periódico.
Estoy leyendo el diario."
- What are you doing?
I'm reading the newspaper.

"- Mañana hay un concierto
- Cómo lo sabes?
Lo decían en el diario.
Lo decían en el periódico."
- Tomorrow there will be a concert
- How do you know it?
It was said in the newspaper.

Diario: daily (like something that happens everyday).
Periódico: (like something that happens recurrently, every so often is repeated).

"A diario, voy al bar": Daily, I go to the bar.
"Me duele la cabeza. Es algo diario": I have a headache. it's a daily thing.
"Este ascensor se estropea mucho. De vez en cuando se para. Es algo periódico": This elevator (or lift😉) breaks down a lot. From time to time it stops. It's a recurrent thing".


Referring to maths: "periódico" is the decimal figure, or a set of them, that is repeated.