As for the differences, road cycling shoes usually have a larger cleat and stiffer sole while gravel cycling shoes come with treads. A larger cleat allows road shoes to grip in a much more aggressive manner, which may provide a stable platform but may also be a little more costly. A good compromise is gravel shoes with treads that can be used on the road as well. If your objective is not focused on competitive racing, then gravel shoes are likely what you would like.