We are trying our best to keep the Server/Data Center/Cloud versions aligned. However, there is some extra functionality that is available (at least, for now) only to one or another version. They are the following:
Conditional issue-related reminders
Integration with Configuration Manager app
My Reminders gadget
Also, a united reminder to be created in the Cloud version in case of several addressees when the separate reminders to be created for each one in the On-premise version.