Breadcrumbs
There has been a lot of dispute, over the years centuries millennia on whether the guardian angel is the same as, or different than, one's higher self. This disagreement goes back at least as far as Plato himself, who seemingly takes the former stance in the Timæus [90A] and the latter in the Republic [in the Myth of Er, 620E].
I have wondered about this also, and some four or five years ago I asked my own angel about it. They characteristically and cryptically answered (with a wink, no less!) that they are both me and not me. (That is not even an answer, it is a koan! Such a tease.) I have long pondered this and have not made proper sense of it.
I was going back over Plotinus this evening when I came across a line of his in Enneads III iv "On Our Allotted Guardian Spirit" 5: "For that this guardian spirit is not entirely outside but only in the sense that he is not bound to us, and is not active in us but is ours, to speak in terms of soul, but not ours if we are considered as men of a particular kind who have a life which is subject to him [... .]"
I missed this on my first read-through, but Plotinus is saying the same thing as my angel did! I still don't quite understand, but at least I have a trail of breadcrumbs to follow...