I've been pondering this question for awhile. What are the psychological differences between us men that cause us to be attracted to different types of women.
I assume that neither of you actually knows that woman, so the only "type" of person she could be to either of you is an actress (along with her other attributes: mother of 6 children, special envoy for the United Nations High Commissioner for Refugees (UNHCR), humanitarian, etc.).
People often put someone on a pedestal for various reasons, and redefine their preferences later.
Perhaps she has done something that your friend admires and that increases his opinion of her, while doing nothing to actually increase her attractiveness.
This article: "10 Highly Attractive Traits In Women (That Have Nothing to Do With Looks)" (which is hardly a definitive and reliable source) explains a few things that are probably relevant to an answer: kindness, positivity and sense of humour, passionate about her pursuits, confidence, emotional responsibility, decisiveness, her own sense of style, gentleness - not that you've seen her on her 'bad days', it's really a matter of perception.
Wikipedia (another non-expert) has a well thought out webpage and a section on female attractiveness. It lists Jessica Alba as proportional to the most attractive features:
"A study by the University of Toronto found that specific ratios in the female human face correlated with attractiveness. The distance from pupil to pupil was 46% of the distance of the width of the face (from inside edge of ear to inside edge of ear). The distance between midpoint of eyes to midpoint of mouth was 36% of the length of the face from the chin to the hairline. Researchers found that ideal measurements, in proportion to the overall size of the face, were close to the average of all female profiles.".
The website MorphThing has closeups of each of them, and a mock-up of their faces combined:
If you're friend comes back with, "Oh yeah, I didn't mean Angelina Jolie, I meant Jessica Alba" - well that's another thing that happens. I know females whom are better looking than either of them, not as accomplished but 'better looking'.
Beauty is in the eye of the beholder. Both of them are 40 and have a few children from other men, so I'm going to pass. I know females whom appear quite beautiful but make a lot of mistakes, covering for them wouldn't be worth the trouble.
I agree with you that your friend could have picked someone else. The wikipedia link provides many links to various studies as well as mentioning that beyond 'general traits' that opinions differ in different parts of the world.
This question is older than Aphrodite of Milos and Aphrodite of Knidos. So the answer is not "opinion based" the best explanation seems to be that the layperson seems to believe that they can look at facial features and body appearance, from that they can make a judgment about fertility; that being the deciding factor based on genetic selection. I (we) believe that some people are not so skillful as others.