If you upgrade your MCU 5320 with the TelePresence Server migration software, this will turn the MCU into a TelePresence Server so all features and functionality will be that of a TelePresence Server and not an MCU. See the Running TS Software on MCU 5300 Series install guide on how to convert your MCU to a TelePresence Server if you're interested.
Here are two good discussions comparing the MCU and TelePresence Server platforms, one of them specifically about migrating from one to the other.
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The cisco_ts_3.1_1.98_for_mcu_5300 software is for migrating an MCU 5300 Series to a TelePresence Server. While the cisco_ts8700_3.1_1.98 software is specifically for hardware that is already running TP Server software, such as the various TelePresence Servers models listed here, this includes MCUs that were migrated to run TP Server software such as the MCU 5300 Series and MCU MSE 8510.