"I go to the park."
Translation:Eu vou ao parque.
actually, there is a difference. In spoken language they mean the same, not for the written language. If you use a that means you'll come back ( vou ao médico, vamos ao Brasil - meaning a round-trip) and if you use para it means to go and not intend to come back (vou para o Brasil - to live there). However, to be true, not many natives know about it so they use them for any context.