A Spanish postal code is five digits whose first two identify the province — 28 for Madrid, 08 for Barcelona, 41 for Sevilla — running from 01 to 52 in the same order the provinces are numbered. That makes the code partly self-validating: a code beginning 28 beside a Catalan city is wrong, and you can catch it without a postal database. It also means leading zeros are load-bearing, exactly as in Germany: 08001 is Barcelona and 8001 is nothing.
The line most international forms lose is the second one. A Spanish urban address routinely carries a floor and a door after the street number — Calle Mayor 10, 3º B means the third floor, door B — and in an apartment building that is not extra detail, it is the part that distinguishes one home from twenty. A form with a single street-address field and no second line forces the customer to jam it in somewhere, and a form that silently truncates loses the delivery.
Spanish addresses may also add the province on its own line after the town, in brackets or plain, when the municipality is small enough to be ambiguous. Several hundred Spanish municipalities share names with others in different provinces, so this is disambiguation rather than decoration.
Two things about the rest of the record. Spain has no telephone trunk prefix — the nine digits you dial domestically are the nine digits after +34, with nothing to add or strip, which makes it one of the easy countries to convert to E.164 and a good control case beside France, where a leading zero has to come off. And Spanish names carry two surnames, paternal then maternal: measured over 20,000 draws from this generator's own Spanish pools, 100% of the surnames contained a space and the longest full name ran to 48 characters. If your name field is one column of twenty characters, Spain finds out first.