The Humidity and Relative Humidity both are water present in the air in the form of vapor. The main difference is measurement of water vapor in the air. The humidity also known as absolute humidity. The absolute expressed as grams of moisture per cubic meter of air (g/m3).
The Relative humidity is expressed as amount of water vapor in the air as percentage at its current temperature.
The Absolute humidity not depend on temperature but Relative humidity depend on temperature.
Based on area (coastal area, desert) absolute humidity will change, based on temperature Relative humidity will change.