Python script to clean up a list of urls from duplicates

Need help with the following python code.

The goal is to compare two lists of URLs and creating a third list that doesn't contain duplicates.

Existing code:

1. Getting list from an XML file:

def get_urls_of_xml(xml_url):
r = requests.get(xml_url)
xml = r.text
soup = BeautifulSoup(xml)

links_arr = []
for link in soup.findAll('loc'):
linkstr = link.getText('', True)
#print(linkstr)
links_arr.append(linkstr)

return links_arr

2. Getting list from a database (i have this part of code, I can provide if needed)

db_urls_list = []

3. This is the part that i am missing:

Compare the list taken from a database and the list downloaded from XML and create a list that doesnt have duplicates.