Candle oil is not a specific term, but it can refer to either fragrance oils or essential oils that are used in candles. Fragrance oils are synthetic aroma compounds or natural essential oils that are diluted with a carrier like propylene glycol, vegetable oil, or mineral oil. They are engineered to create a nice, long-lasting "scent throw" and are often used in candles, perfumes, soaps, and other scented products. Essential oils, on the other hand, are made from various aromatic plants or tree roots and undergo an intensive manufacturing process to extract the oil. They are considered “natural” fragrances and can have aromatherapeutic benefits. However, candles with essential oils dont retain their scent as long as candles with fragrance oils.

In summary, candle oil can refer to either fragrance oils or essential oils that are used in candles. Fragrance oils are synthetic aroma compounds or natural essential oils that are diluted with a carrier, while essential oils are made from various aromatic plants or tree roots and can have aromatherapeutic benefits.