Kind of implied .
Actually you are incredibly wrong on eight hundred accounts... Well not really, just one...
How could Roxas and Ven be the same age, if Roxas hasn't been created/born yet.
^^^
(Thats is if you ment it in that type of way)
(If not)
It has been stated that Ven is not Roxas and as such does not resemble him, yes his appearance may be the same and there is most probably a link between the two but I am sorry but you can not jump to conclusions like that without stating all the facts.
Don't presume they are the same age, we do not know yet.