Four of the following five are alike in a certain way as per the given arrangement and thus form a group. Find the one that does not belong to that group.

Study the following information carefully and answer the question given below: Nine boxes viz. S, T, U, V, W, X, Y, Z and R are kept one above another but not in the same order. The box kept at the bottommost position is numbered as 1 and the box kept at the topmost position is numbered as 9. At most two boxes are kept below box U. Three boxes are kept between R and the box which is kept immediately above box U. W is kept two boxes above box R. Two boxes are kept between W and S. Box Z is kept immediately below box
X. Box Y is kept three boxes below box
X. Box T is kept above box
V.