The Gregorian and Hebrew calendars are out of sync, as one is solar and the other is lunar.  In 1954, the 28th of July corresponded to 27 Tammuz.  This is different every year.  This year (2018) the 28th of July corresponded to 16 Av, but your friend's Hebrew birthday is indeed 27 Tammuz, as that is the date she was born in 1954 (Hebrew year 5714).  So her Hebrew birthday is always 27 Tammuz, which will very often not fall on or even near July 28th - this year it was July 10th.  She may celebrate whichever one she wants, or both if she wishes!   (If she she was born after sunset on July 28th then her Hebrew birthday is actually 28 Tammuz.)