Aida, I too see very little difference between the two sizes. However, the sleeve length is better on the smaller size so I vote for that one. If the bigger size were truly bigger, like intentionally bigger, I would like that too but they both look like a fitted style to me and to my eye the smaller size fits better in the sleeves. If you go for a "fitted" or "tailored" style of clothing, I vote for the garment that fits better.
But I know there are a bunch of different opinions so, take with a grain of salt.