To get a vector output:
A = randi(9, 1, 4) % Create Vector
Dif = A(:) - A(:)'; % R2016b & Since
Dif = bsxfun(@minus, A(:), A(:)'); % R2016a & Previous
Out = (triu(Dif)+tril(nan(size(Dif))))';
Out = Out(~isnan(Out))'
so for example:
A =
8 9 7 2
Out =
-1 1 6 2 7 5
EDIT — Corrected comments. Code unchanged.
