They have a similar art style and color theme. Both are accompanied by music and lack dialogue. Both are surreal and mysterious; and share a calming and somewhat bittersweet atmosphere. Also, both focus on only one central character, and the world through that character's eyes.
they are both very artistic and poetic and driven by an awesome musical score.. so if you can't appreciate something that's more interpretive and artsy then this probably isn't for you.. they feel something like a daydream, something pleasant and floaty.. yea, floaty.. hah.. anyways they're both great.
Yokohama Kaidashi Kikou is the quintessential tranquil anime. It paints a picture of wonderfully laid back countryside life, with warm relationships between characters. And of course, there is the relaxingly slow pace, unmatched in anime as far as I'm concerned. Most of that can also be said for The Diary of Tortov Roddle. In this anime, a traveler goes on a journey across rather peaceful landscapes to all sorts of different places. There is no dialogue, only the travel notes written by Mr. Roddle. Both shows will warm your heart.
Angel's Egg is a lot more "deep" than Tortov Roddle, but both of them transport the viewer to a fantastic and surreal world. If you enjoyed the sights and sounds of Tortov Roddle, then you will love Angel's Egg for its artwork alone.
While at first glance these shorts seems to be on opposite ends of the spectrum - Kigeki a fictional story set in the historic Irish War of Independence, Diary of TR set in a surrealist world with no ties to reality - there exists a very similar feeling between them: The style and colors are luminously muted, both stories leave the viewer with no real sense of closure, and both create a strong attachment to the characters with very little (or no) dialogue.