As we know that the vector equation of a line is of form r = a + mb where a is the position vector through which line is passing, b is a vector parallel to line and m is a constant.
If two equations of line
r= a1 + mb1
r= a2 + nb2 are given,
then to find the distance between these lines first we have to find,
b1 X b2
a2 – a1
| b1 X b2 |