Galaxy Tab S 8.4 will roll out both over-the-air as well as through Samsung Kies. You can check for the OTA update by going to Menu >> Settings >> About device >> Software update >> Update. If you're the patient type, you can wait for the system to notify you when the update is available for download. The update clocks in at a hefty 1.5GB.The Android 5.0.2 firmware for the Wi-Fi only
If you're using an LTE version of either Galaxy Tab S version, you're currently out of luck, as you'll probably have to wait a little more before getting a taste of Android 5.0 Lollipop on your tablet.
Until Android 5.0.2 reaches your device, you can learn all about the new features from the following video: