Are the planes represented by the equations x+4y−5z=18 and 2x+8y−10z=45 the same plane, different planes or neither?

x+4y−5z=18

and
x+4y−5z=22.5
well, look at where x = 0 and y = 0
then z = -18 / 5 for the first and z = -22.5 / 5 for the second
They are different, but perhaps show similar slopes :)

Are the planes represented by the equations x+4y−5z=18 and 2x+8y−10z=45 the same plane, different planes or neither?

x+4y−5z=18

parallel planes, since they have the same direction numbers but no common point.