Similarities:
- Both are cleansing agents.
- Each ion of both soap and detergent consists of a long chain of hydrocarbon part which is hydrophobic and an ionic part which is hydrophilic.
- Both can reduce the surface tension of water, thus, allowing water to wet the surface.
- The cleansing actions of both soap and detergent enable oil droplets to disperse in water and form an emulsion that will not redeposit on the surface.
- Both are effective as cleansing agents in soft water.
Differences:
- Soap is biodegradable while detergent is not biodegradable (can cause environmental pollution).
- Detergent is an effective cleansing agent in hard water, soft water and in acidic solution but soap is only effective as a cleansing agent in soft water.