During the early days of the pandemic United allowed people to choose between electronic travel certificates (ETC) and future flight credits (FFC) when cancelling a flight. I wrote about the pros and cons of taking either option here. Of course you should never cancel flights before the day of departure, as you can get a cash refund if United cancels or changes the flight before you cancel the reservation.
Since then, United has made FFC the default option for when you cancel a flight, though if you HUCA you can still trade that for an ETC. You also get an ETC for the change if you exchange an FFC for a flight that costs less than the value of the FFC.
United has also added the ability to view FFCs and ETCs from your account.
In general, ETCs are more flexible, more valuable, can be combined with other ETCs, and last longer, but a major limitation has been that they couldn’t be used for travel on a partner airline.
But now United has removed that restriction and they allow ETCs to be applied towards partner airline flights. For example here is a $25.49 ETC applied towards a Lufthansa flight on United.com:
Now, if only United would restore the ability to cancel flights for an ETC without having to HUCA!