What's the differences between the two version of oracle client download file, "client" and "client home"?
LINUX.X64_193000_client.zip is a fully featured installer where you can choose what to install and where, then the installer copies the files to the destination and registers the client.

LINUX.X64_193000_client_home.zip is an "image" of and "Administrator" type installation, that you unzip to the destination folder then register it. 

Simplified Image-Based Oracle Database Client Installation


  Starting with Oracle Database 19c, the Oracle Database client software
  is available as an image file for download and installation. You must
  extract the image software into a directory where you want your Oracle
  home to be located, and then run the runInstaller script to start the
  Oracle Database client installation. Oracle Database client
  installation binaries continue to be available in the traditional
  format as non-image zip files.
  
  As with Oracle Database and Oracle Grid Infrastructure image file
  installations, Oracle Database client image installations simplify
  Oracle Database client installations and ensure best practice
  deployments.


About Image-Based Oracle Database Client Installation


  Starting with Oracle Database 19c, installation and configuration of
  Oracle Database Client software is simplified with image-based
  installation.
  
  To install Oracle Database Client, create the new Oracle home, extract
  the image file into the newly-created Oracle home, and run the setup
  wizard to register the Oracle Database product.
  
  You must extract the image software (client_home.zip) into the
  directory where you want your Oracle Database Client home to be
  located, and then run the Setup Wizard to start the Oracle Database
  Client installation and configuration. Oracle recommends that the
  Oracle home directory path you create is in compliance with the Oracle
  Optimal Flexible Architecture recommendations.
  
  Using image-based installation, you can install Oracle Database Client
  32-bit and 64-bit configurations of the Administrator installation
  type.
  
  As with Oracle Database and Oracle Grid Infrastructure image file
  installations, Oracle Database Client image installations simplify
  Oracle Database Client installations and ensure best practice
  deployments. Oracle Database Client installation binaries continue to
  be available in the traditional format as non-image zip files.