Traffic(pcap file) size gap between client and web(hidden service) server

I have some questions about traffic size difference. I construct my hidden service server using apache on ubuntu16.04. Client’s environment is also same. When client access to hidden service server called “.onion” using Tor Browser, client and hidden service server collect packet simultaneously. The method to collect simultaneously :

  1. client and hidden service server communicate with each other regardless of the Tor network.
  2. When hidden service server notice that client write something, Hidden service server start collecting packet.

The result of using this method is “.pcap” files of client and hidden service server. At that time these two “.pcap” file’s sizes have gap about x8 or more. Why this situation is coming?