[2019] Difference between ailments and debuffs?

Debuffs, like Buffs, are a category of timed effects. Debuffs are negative and involuntary (stuff that has negative downsides but which you chose to apply to yourself like Blood Rage is not a Debuff). Debuffs include Ailments, Curses, most forms of damage over time, and several other effects such as Hinder or Maim. Debuffs can be identified by the icon for their effect - if it has a red border, it's a Debuff (similarly, things with green borders are Buffs). If an effect has an icon without that red border, it isn't a debuff.

Ailments are a specific subset of debuffs. Each ailment is associated with a damage type, and is usually inflicted as an on-hit effect, with the strength or duration of the ailment being based on how much damage of the matching type was dealt in the hit. Some of them can also be inflicted in other ways.

These are all the ailments in PoE:

• Bleeding
• Ignite
• Scorch
• Chill
• Freeze
• Brittle
• Shock
• Sap
• Poison

Nothing else is an ailment.