With 33 years in Spain I offer the following:
A Gestoría is a place where you find gestores, asesores fiscales and perhaps others. A gestor is a trained "pen pusher" who is registered just like a lawyer. He knows at any moment how many photos, which forms and which documents you need to complete a particular administrative procedure - eg getting a driving licence or changing the ownership of a car. He issues a "justificante profesional" to allow you to drive whilst your car papers are processed. Spanish bureaucracy is so complicated that he earns his fee! Ask any old hand about "pagos or timbres del estado" and you'll understand.
An asesor fiscal (tax adviser in English) will deal with tax returns and related matters. Again he is trained and registered.
An abogado (lawyer): Anything that involves the Spanish courts or notaries may need a lawyer. Notaries are in fact lawyers themselves but act impartially rather than acting for one or othe party. All are registered in a Colegio de abogados.