Welcome to the Community,
the binaries are the same for each edition, it's only the license key which makes the difference. VMware provides downloadable iso images for different - but not for all - updates/builds. You can however update/patch ESXi to the latest build if you want. As an alternative to downloading the patches from the VMware website, you can use e.g. the PowerCLI script from the v-front.de site to create your own installation image, or offline bundle.
André