The chef_gem and gem_package resources are both used to install Ruby gems. For any machine on which Chef Infra Client is installed, there are two instances of Ruby. One is the standard, system-wide instance of Ruby and the other is a dedicated instance that is available only to Chef Infra Client. Use the chef_gem resource to install gems into the instance of Ruby that is dedicated to Chef Infra Client. Use the gem_package resource to install all other gems (i.e. install gems system-wide).