Always though WHRP nailed it:
Strength: Defines a character’s brawn and physical strength. Strength is used to determine the outcome of a number of physical skills and tasks, such as climbing, breaking down a door, or hitting hard enough with a melee weapon to inflict damage.
Toughness: Defines a character’s endurance, constitution, and vigour. Toughness is used to shake off damage, recover from injuries, and resist the effects of toxins or the ravages of disease.
Agility: Defines a character’s dexterity, coordination, and gross motor control. Agility is used for a variety of physical skills and tasks, such as balance, stealth, picking locks, and the ability to wield ranged weapons with accuracy.
Intelligence: Defines a character’s general intellect, reasoning, and powers of deduction. Intelligence is used for a variety of academic and knowledge-based skills, and is important for arcane spellcasting.
Willpower: Defines a character’s nerve, discipline, and force of will. Willpower is used to resist effects such as fear, remain disciplined under trying conditions, and is important to controlling the Winds of Magic or generating favour with a deity.
Fellowship: Defines a character’s general charisma and ability to apply their personality. Fellowship is used for a variety of social skills and actions, such as charm and guile, as well as to beseech the gods when invoking divine blessings.