The side list here for example Cassandra Cain as 1 Year younger than Tim Drake, in the comics she is two year older than him. Or they lit for example J.J. Thunder at the same age as Cyclone. And Arrowette is also listed as 4 years younger than Tim despite them being the same age in the comics.
That is due to how the ages were determined on this side. The creator(s?) made a chronology of events based on the time that is said to pass in a story or between certain events, than took the best (or earliest) reference for the age of a character at a defined point of this timeline (often the age during their origin story) and used this to calculate their birthdays.
The problem is that at some point in the early to mid 90s, the character started to age to age much slower than the time the universe passed, Tim Drake turned for example 15 at some point between Knightfall and No Man's Land but didn't turn 16 until Hush, despite the fact that allready No Man's Land lasted in universe a year, and an other year passed between No Man's Land and Fugitive. And that has the consequence that relative ages of characters that were already active around COIE and characters that were introduced in the late 90s and 2000s in this list on this side don't really match with the comics.