The solution is from this link
With a little modification
closest-point-from-long-list-to-a-point-in-a-shorter-list
# Load the Python Standard and DesignScript Libraries
import sys
import clr
clr.AddReference('ProtoGeometry')
from Autodesk.DesignScript.Geometry import *
# Inputs
short_list = IN[0]
long_list = IN[1]
# Output list
result = []
# Loop check for each point in the short list
for s in short_list:
# List for distances
dist = []
for l in long_list:
# Distance to point s
d = Geometry.DistanceTo(s,l)
dist.append(d)
# Lowest distance in list
min_d = min(dist)
# Index of lowest distance in list
min_ind = dist.index(min_d)
# Get the closest point from the long_list
closest_p = long_list[min_ind]
# Add the point to the results, as it is the closest to the point from the short list
result.append(closest_p)
# Output the results
OUT = result