what is the difference between aqui and aca - here
I've seen both aqui and aca used for here. Do they have different uses?
2 Answers
Excellent question, amigo.
A huge mistake made in Spanish is...they are not interchangeable!!
"Aquí " and "acá" both refer to a location near the speaker.
However, "acá" is used with verbs. Fabio, come here -- "Fabio, ven acá"
Then, "aquí" is used in the remaining situations. The cookie is here -- La galleta está aquí
In order of "distance" [closest to farthest], it goes: aquí/acá, allí, allá, aquel/lla
Here are some other posts on SpanishDict regarding this topic.
This is one of the most difficult concepts in Spanish [for me, anyway 
], so great question. I hope I helped you!
If you put aquí vs acá in the Answers search box, you find several interesting threads on this topic. 
