Even-though you and your beloved friend born in the same sign but position of Sun may be in varies Because
Sun moves one degree in a day.
The Sun will stay one month in one sign i.e 30 days to travel 30 degree.
In this time sun covers 9 navamsa, which is ruled by different planets, this shows strength of Sun.
if you date of birth are different Sun position is different even though sun sign is same.
Our Researches shows even twins born difference of 5 min have a different characters and personalities.
then how we can expect the same sun sign individual to show the same characteristics.
Apart from the above The ascendant is also a play an important role.
The ascendant changes roughly every two hours.
Lot of things are interlinked, some of few i mentioned above.