not entirely true. The DL of St John is very very similar in almost all cases, but differences do arise. Like: certain Ukrainian priests SAYING the DL in English rather than singing it; the truncations of the Ruthenian version (Shorter litanies, mostly); or the priest’s choice of the Antiphon hymns or the typical psalms; Melkites occasionally using Intinction by dipping strips of the precious body into the precious blood instead of immersing the particles and using a spoon; whether the entrances are out the deacon door and straight to the royal doors, or out the deacon doors, around the congregation, and back to the royal doors; DL of St. John or DL of St. Basil; Matins, Divine Praises of the Third Hour, Simplified Divine Praises, or no Divine Praises prior to Divine Liturgy.
Lots of little differences.
True, most of them on par with the differences between the Roman Missal of 1962 and the Dominican Missal, or the Carmelite Missal… if you are not paying attention, and know them, it may surprise you; if you don’t know them, you may even not notice the differences.