When I overlay the river with the DEM you can see that it does not match at all.
Perhaps if the vector layer is flipped horizontally and vertically, rotated and perhaps enlarged is may come a bit closer, but you shouldn't do that:
This may be related to the coordinate system of one or both of the inputs and interpolate the contour lines followed by comparing both sources would not make much sense, since this will generate huge differences due to the mismatch of location.