Facebook profile - view as?

[JellyIsCool]

When I go to "View As" on my Facebook timeline (But only while viewing as one specific person I know), instead of it showing my activity box at the top right of the timeline (the one which shows roughly three things I've liked, or people I've become friends with recently etc) it shows a list of my profile information, like my birthday, where I'm from etc.
Why is this? Is it because I've inadvertently changed my privacy settings for this specific person, or is it something they have done to view less of my profile information? thanks in advance!
I don't feel that answered my question at all Sewrob, or you at least you definitely misunderstood what I was asking, or didn't read the text below the main question.

I know exactly what "View As" means and does. But I was wondering *what could have caused the aforementioned situation*, whereby if I do "view as - person x", instead of it showing my recent activity at the top of my timeline (like something I've liked recently, or people I've become friends with) it shows some of my basic profile information like my birthday and where I'm from, while for any other friend on my friends list they see my activity. (I'd like to emphasise that this only pertains to viewing as one of my friends specifically, rather than anyone else on my friends list). I have no recollection of ever changing my privacy settings specifically for this person, so I was wondering why this happened.