What is the deference between Edema and Oedema

What is the deference between Edema and Oedema

Edema is swelling caused by excess fluid trapped in your body’s tissues.

oedema is a related type of swelling that affects deeper layers in your skin, often around your eyes and lips.

Both of them mean same thing just that (oedema) British why the other one(edema) is American spelling .All of them is accumulation of excesses water

Oedema is a disease of the kidney result from excess water in the body which appears to accumulate in the ankle and disturbs the normal functions of the kidney,

Fluid retention d/f American British Nigerian grammer