As of vSphere 4.0, there is a different linux.iso for ESX and ESXi.
The ESX linux.iso contains both the RPM and tar formats. However, to reduce the footprint of ESXi, the linux.isono longer contains the RPM installer. RPM containing VMware tools for linux was deprecated in favor of Operating System Specific Packages(OSPs) . VMware Tools OSPs allow you to use your operating system's native update mechanisms to automatically download, install, and manage VMware Tools for the supported operating systems. For more information regarding OSPs,
Installation Notes for This Release in the ESXi 4.0 Release Notes and Install VMware Tools on a Linux Guest with the RPM Installer in the vSphere Basic Administration Guide both discuss this change.
Note: The ESXi 4.0, ESXi 4.0 Update 1, and ESXi 4.0 Update 2 have the option to download the VMware Tools CD image for Linux guest operating systems ISO, which contains both the RPM installer and .tar format for the Linux VMware Tools. However, ESXi 4.1 does not have the RPM installer in the VMware Tools CD image for Linux guest operating systems ISO.
Note: The VMware Tools RPM installer, which is available on the VMware Tools ISO image for Linux guest operating systems, has been deprecated and will be removed in a future ESX release. VMware recommends using the tar.gz installer to install VMware Tools on virtual machines with Linux guest operating systems.
Based on VMware KB 1024047