The first thing would be salary. If you join as a fresh grad, you will start off on the MAS payscale and progress along the way. If you join as a mid-career, HR will naturally have to try to match or give a suitable increment for you to join (same with any other job tbh).

If you talk about non-work specific learning, MAS is a great place. There is a lot of emphasis on learning and you can even join various modules (with officers from other departments) and aim towards completing the MAS diploma.

If you talk about work-specific learning, then this is obviously dependent on which department you are in. As a mid-career, you were hired because you have some relevant knowledge and experience. However, you obviously have to learn the parts of the job that you are not so informed about. As a fresh grad, you have no experience, thus you have to learn job from scratch.

I cannot understand the point of your question (to quote a certain minister). What exactly are you trying to ask?