python3 取 baidu 关键字十条结果为何与实际通过浏览器搜索的结果不同？

#coding:utf-8
from collections import Counter
import requests
from bs4 import BeautifulSoup
from urllib import request
import urllib
url = 'https://www.baidu.com.cn/s?wd=' + urllib.parse.quote('python3') + '&pn='  # word为关键词，pn是百度用来分页的..

headers = {    
'User-Agent': 'Mozilla/5.0 (Macintosh; Intel Mac OS X 10_13_5) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/67.0.3396.99 Safari/537.36',    
'Connection': 'keep-alive',       
'accept': 'text/html,application/xhtml+xml,application/xml;q=0.9,image/webp,image/apng,*/*;q=0.8'}

r=requests.get(url,headers=headers)
soup = BeautifulSoup(r.text.replace('<b>', '').replace('</b>', ''),'lxml')

url_list=soup.select('div.result > h3 > a')
for i in url_list:
    print(i.getText())

以下是在浏览器搜索python3,前四个结果，当我用python3以上程序取前十结果时，结果内容是不一致的，试过n多关键词都是，哪位朋友能给讲讲原因，是我程序的问题还是百度做了什么，谢谢！