The best way to really tell is to do what others have suggested. If your curious enough you need to get out there compare for yourself. Do yourself a favor though and look at as many examples as possible however. It's fairly easy to see some of the difference once you compare how they look and feel in person. The quality of the leather is the first thing I noticed, but as others have said there are other things that make it worth it to me. Smaller details may not be as obvious at first however. Fit should be your number one priority when choosing regardless.
There are a number of different price levels when it comes to shoemakers, and here again you will have to determine what price range fits your budget, your needs, and likes and desires to be the best for you.. Personally I have a number of shoes from a number of different shoemakers at various different price points to include a few AE shoes. A great part of this was because I liked a certain shoe best than some other, or I wanted to see what this brand was like. I have found the higher up the price range I have gone the happier I have been with the shoes I have purchased. I do have a number of shoes in the mid range price bracket such as Alden, Carmina, C&J, Rider Boot Co, AS, and Vass. For the most part I find these more enjoyable than any of the AE shoes that I own. I also own some from John Lobb, Edward Green, Gaziano & Girling, and St. Crispins. Here again I find these for the most part to be more enjoyable than those in the midrange price bracket.
Keep in mind that not all higher end shoes are created equal however. There tends to be differences between manufactures of shoes just like any other product. John Lobb and Edward Green both make shoes, but the leather John Lobb uses tends to be more malleable than any other shoe I've seen. I personally like the way John Lobb executes the Double Monk, but I tend to like more of Edward Greens shoes and I like the way they burnish their shoes.
The level of interest or excitement you have in regards to these matters is not something another can convince you of, it's something you'll have to determine for yourself.
Edited by dddrees - 7/4/13 at 2:00pm