Simple treats the whole big sheet as one area. Every smaller piece is cut the same way (all “tall” or all “wide” if you allow rotation). The app picks whichever single layout fits the most pieces. Think: one straight grid across the entire sheet.
Advanced allows the sheet to be split into bands (like shelves or columns): one strip might work best with pieces one way up, and the next strip with pieces turned 90°. It never gives fewer pieces than Simple, but it can find extra pieces when the leftover strip is an awkward shape. For neat standard sizes (for example A3 into A4) both modes often match.
