How to filter out partially similar strings from two lists and make one list?
You really need to learn some python :)
with open('/path/list2.txt', 'r') as fin:
    to_keep = set([])
    for line in fin:
        to_keep.add(line.strip())
        
with open('/path/list1.txt', 'r') as fin:
    with open('/path/list3.txt', 'w') as fout:
        for line in fin:
            if line.strip().split(' ')[0] in to_keep:
                fout.write(line)