Air carrier First Officer reported deviating from ATC clearance due to the confusing message format of the CPDLC clearance.

Narrative

On the morning of Day 0 operating Aircraft X at XA:25 while transiting Cleveland ARTCC airspace; a lateral CPDLC clearance was received. This new instruction appeared to be a direct to a fix not in our flight plan; MAYZE; then direct PONCT; which was part of the original route. I proceeded to load the secondary flight plan. However; at first glance the loaded route appeared to differ from the digital message as a random defined waypoint had been created and the fix MAYZE was not there. I decided to instead insert the new routing on the active flight plan; since at first glance this appeared to be a very simple change. Approximately a minute later ATC called to verify the route and advised we were supposed to be flying direct PONCT by now. I replied that our received digital clearance had us going to MAYZE then PONCT. ATC stated it was not MAYZE but rather a point based on bearing/distance from MAYZE. This was something that I then realized after carefully reviewing the digital uplink; but was not readily apparent to me due to the message format. A revised direct to PONCT clearance was issued. The controller stated that we were the second aircraft that morning having a similar issue with this type of CPDLC clearance. I was not advised of a possible pilot deviation; nor was a telephone number to call provided. During this short period of time the Captain had exited the fight deck to use the lavatory. The flight continued to its destination Boston with no further eventualities.