Statistics Building focuses on aspects that alter basic abilities, including but not limited to Hit Points, Speed, Sight, and Charm. Most often, these are innate features a character is born with.
The aspects on the Skills Building page are about boosting your skills, frequently through Insight bonuses. A character might have a talent for certain skills or extra training depending on where they come from.
Defensive Building aspects mostly focus on immunities and resistances, with some for Armor Class and Saves. Most of these represent cultural or environmental factors of a character’s history.
Aspects on the Offense Building list provide bonuses to attacks, including additional Strikes. These are a mixture of genetic abilities and learned, cultural abilities.