The only difference between lymph and interstitial fluid is its location. If the clear, colorless fluid is found in the spaces between body tissues, it is called interstitial fluid. If it is found in the lymphatic system, it is called lymph.
Lymph circulates throughout the body's lymphatic system carrying white blood cells, metabolic waste, fat cells, proteins and dead cell particles away from the interstitial spaces in the body. In layman's terms, the lymphatic system is known as the sewer system of the body, according to the Salutaris Centre for Lymphatic Therapy.
Once the lymph fluid passes through the body collecting waste, it empties into the subclavian vein before entering the heart. Here, it mixes with blood and moves through the blood stream into the kidney. In the kidney, waste is removed from the lymph and filtered into the bladder where it takes the form of urine and is excreted from the body.
A functioning lymphatic system is important to a healthy immune system, as noted by the Salutaris Centre for Lymphatic Therapy. If the lymphatic vessels become damaged or blocked, proteins and wastes can build up in the body. This build-up creates swelling known as edema and can cause pain and difficult movement in the affected area.