Trunk comparison: Audi A4 Avant vs Ford Focus

Key Differences
The Audi A4 Avant offers significantly more usable length: with the seats folded down, the trunk is 11 in (18%) longer, and with the front seats upright even 11 in (36%) longer than in the Ford Focus.
In contrast, the Ford Focus has a significantly greater depth between the loading edge and the trunk floor: +5.1 in (260%).
Smaller differences concern the height of the trunk opening (Audi +2 in / 6%), the loading edge height above the ground (Focus +2.4 in / 10%), as well as minor width differences of about ~0.8 in each.
Impact on Usability
The greater cargo length of the Audi A4 Avant practically means that longer items (e.g., furniture parts, long timber, skis with folded seats) can be transported more easily and loading is overall more flexible.
For moves or when frequently transporting longer cargo, the A4 is noticeably more practical in everyday use.
The significantly greater depth in the Ford Focus means that cargo sits deeper in the vehicle and more volume "below" the loading edge can be utilized.
This is advantageous when bulky but not very long or tall items need to be pushed as far down as possible, or when more cargo space in height under the loading edge is required. At the same time, the deeper position can make loading or unloading heavy items more difficult because they sit lower.
Smaller deviations (opening height, loading edge height, widths) only marginally affect everyday usability: a slightly higher opening in the A4 makes sliding wide parts through a bit easier, the somewhat higher loading edge of the Focus (10%) can be less or more strenuous when lifting into the vehicle depending on direction, but is not a decisive factor compared to the mentioned length and depth differences.