Verdict
Same firmware family, same AMS Lite compatibility, same Bambu Cloud integration. The A1 is $100 more for a 256mm cube vs 180mm. Power draw is similar (100W vs 70W avg). The math is mostly about footprint: if you'll print parts over 150mm in any axis more than a couple times, the A1 saves you the headache of splitting models. Otherwise the Mini is a more accurate value.
Buy the A1 if: you'll print full-bed plates of small parts (8-12 minis at once), or you'll print single parts over 150mm.
Buy the A1 Mini if: tight desk, mostly small functional parts and figurines, electricity costs matter (the smaller bed warms up faster and uses ~30W less averaged).