a = (1:5)';
b = (4:10)';
[i2,i1] = ndgrid(b,a);
out0 = [i1(:),i2(:)];
out = out0(abs(diff(out0,1,2)) > eps(100),:);
or
a = (1:5)';
b = (4:10)';
idx = fullfact([numel(b),numel(a)])
out0 = [a(idx(:,2)),b(idx(:,1))]
out = out0(abs(diff(out0,1,2)) > eps(100),:);
EDIT
a = (1:5)';
b = (4:10)';
c = [15 17 18]';
d = [20 21 22]';
data = {a,b,c,d};
k = cellfun(@numel,data);
idx = fliplr(fullfact(fliplr(k)));
t = cumsum(k);
idx2 = bsxfun(@plus,idx, [0 t(1:end-1)]);
d2 = cat(1,data{:});
out0 = d2(idx2);
out = out0(any(abs(diff(out0,1,2)) > eps(100),2),:);
