UCAS doesn't tell them, if that's what you're asking. They would see that you're applying a year later than usual obviously, but they won't know for sure if you're a reapplicant or just took a gap year. If you're applying to some of the same places as last time there is a chance the admissions tutors will remember you, especially if they interview you a second time.
As for any advantage, I don't think there is any just for being a re-app. I applied last year for Vet Med and asked those questions just in case (now applying for different course anyway) and opinions varied. Bristol told me that they quite often admit people they rejected first time round if they have got more experience and are more mature. Whereas Cambridge (who only really care about the academics tbh) said 'Well, if we don't want you one year, what makes you think we'll want you the next year?'.
So it depends on the individual unis. But that only really applies to unis you applied to last time, the others won't know.