Atletico Madrid has a home jersey which is being used for matches in La Liga and in the UCL a like. However, while the front of the jersey is the same for both tournaments the back has a different design. The back is striped in La Liga version while it is solid red in the UCL version.
The printing is also different. In La Liga it is blue with a white outline.
In the UCL Atletico has an all white name and number set. Maybe it is in fact the printing style from the 15/16 season which is re-used for the UCL matches during the 17/18 campaign.