crear vs creer
One letter apart, completely different meanings — crear is to create, creer is to believe. Constantly confused in writing and sometimes in speech.
crear
To create — making something that didn't exist before.
Han creado una aplicación nueva.
They've created a new app.
Creation of something — the act of bringing it into existence.
El artista crea desde la experiencia.
The artist creates from experience.
Abstract creation — artistic production. No confusion with creer here.
Esto crea problemas.
This creates problems.
Generating an outcome — sometimes crear = to cause, generate. Very natural.
creer
To believe, to think (opinion), or to believe in something — the cornerstone opinion verb.
Creo que tienes razón.
I think you're right.
The most natural 'I think' for opinions. Enormously common.
No creo que sea verdad.
I don't think it's true.
Negated creer reliably triggers subjunctive. One of the clearest rules in Spanish.
¡No me lo creo!
I can't believe it!
Reflexive creerse = to believe something about yourself or to believe something at all. Very expressive.
Tricky bit
The typo/slip of 'creo una empresa' (I believe a company??) instead of 'creo una empresa' — wait, those are spelled the same in present tense first person! The confusion hits hardest in other forms: 'creó' (he created) vs 'creyó' (he believed). The accent makes all the difference.