They both involve a predictor step that uses Euler’s method with a full step size, h, for the midpoint method and a half step size, h/2, for Heun’s method.

Neither method involves a corrector step.

The midpoint method involves a corrector step whilst Heun’s method only has a predictor step.

They both involve a predictor step that uses Euler’s method with a half step size, h/2, for the midpoint method and a full step size, h, for Heun’s method.

The midpoint method involves a predictor step whilst Heun’s method only has a corrector step.

They both involve a predictor step that uses Euler’s method with a half step size, h/2.

They both involve a predictor step that uses Euler’s method with a full step size, h.

Heun’s method involves a corrector step whilst the midpoint method only has a predictor step.