\vec{AB} = p \vec i + q \vec j + r \vec k

A = (0.3751960460135084, 1.2495488695461319, 0.9576200000000004)
B = (-3.641964244208701, -2.3192313477602795, 3.3019100000000003)
p = Vector((x(A), y(A), z(A)), (x(B), y(A), z(A)))
q = Vector((x(B), y(A), z(A)), (x(B), y(B), z(A)))
r = Vector((x(B), y(B), z(A)), (x(B), y(B), z(B)))
u = Vector(A, B)