Two answers to the same question
If you walk up to the Giorgio Armani counter wanting one bottle, these are the two you will be handed, and they point in opposite directions. Acqua di Gio is the fresh aquatic that basically invented the modern "clean marine" genre and still sells by the truckload. Armani Code is the warm, sweet, spicy evening scent for when you want to smell less like the ocean and more like intent. One is a daytime workhorse; the other is a night-out closer.
How they smell, side by side
Acqua di Gio (EDT) opens on bright bergamot and a cool, salty marine accord — that just-out-of-the-sea freshness — over light aromatic herbs, drying to a clean woody-musky base. It is the benchmark aquatic: versatile, universally flattering, and made for heat. Our full Acqua di Gio review covers the concentrations.
Armani Code goes the other way entirely: a warm, sweet-spicy oriental with bergamot up top giving way to a soft, tonka-and-tobacco warmth with a hint of leather. It reads seductive, cozy and grown-up — a scent built for close range and dim light rather than bright midday. See the Armani Code review for the details.
Season and occasion
This is the easy part. Acqua di Gio is a spring-and-summer, daytime, office-and-anywhere scent; warm skin only makes its marine freshness read cleaner. Armani Code is an autumn-and-winter, evening, date-and-dinner scent; the cold air keeps its sweet warmth from turning heavy. If you wanted a rule of thumb: Gio before 5 p.m. and in the heat, Code after dark and in the cold.
The honest cons
Acqua di Gio's knock is familiarity — it is so common that it can read as "safe" or even anonymous, and the EDT's longevity is only moderate. Armani Code is sweeter and can feel dated or "too much" in warm weather or a bright office, and its close-range warmth means it is not built to fill a room. Pick the one whose weakness you can live with, because both are genuinely good at the job they were made for.
Buy Acqua di Gio if you need a versatile daily driver
If you can own only one and you want maximum flexibility — work, dates, heat, anywhere — Gio is the safer first bottle. It is the definition of an all-rounder and it will never be the wrong choice for a daytime event.
Buy Armani Code if you want a night and cold-weather scent
If you already have a fresh scent covered and want something warmer and more seductive for evenings, Code is the move. It is a closer, cozier, sexier fragrance and it shines exactly where Gio runs out of steam. Together they cover almost your whole calendar; see the Armani lineup for where each sits.