“Attorney-at-law” has sometimes been mistranslated as licenciado en Derecho. But a licenciado en Derecho has completed an undergraduate law degree (similar to the LL.B. or “Bachelor of Laws” awarded at British universities) but may (or may not) decide to practice law. In contrast “attorney-at-law” is the term generally used in the US to denote a lawyer who is engaged in the practice of law, a “practicing attorney” (ejerciente or abogado en ejercicio). A practicing attorney must of course hold a law degree (licenciatura en Derecho) but, in fact, many licenciados en Derecho are engaged in professions other than the practice of law.
It should perhaps be noted that with the adoption of the European Union’s Bologna Process, Spanish universities have phased out their licenciatura programs and now offer a Bologna-compatible undergraduate degree called grado. Thus a law degree is now known as grado en Derecho and those who graduate in law now are called graduados en Derecho rather than licenciados.