According to embodiments of the present document, a prediction procedure may be performed for image/video coding, and the prediction procedure may include symmetric motion vector differences (SMVDs) and merge mode motion vector differences (MMVDs) according to an inter prediction. The inter prediction may be performed on the basis of reference pictures of a current picture, and types (e.g., a long term reference picture, a short term reference picture, etc.) of the reference pictures may be considered for the inter prediction. Therefore, performance and coding efficiency in the prediction procedure can be improved.