This is a weird thing I've wondered for a while now.
What kind of data does OS X store in an Alias file? And why is an Alias invariably much larger in file size than a Symlink, which looks and acts pretty much the same way as an Alias with a few differences.
For instance, I did this test...
In the image above you see an Alias and a Symlink. Both point to the same folder. There is no custom icon. Yet the Alias file is almost 6MB while the Symlink is a few bytes. A Symlink is basically just a link, i.e. a string of text telling the system where it's pointing to. But what the hell is in an Alias that would make it 6MB?
Obviously there's metadata Aliases can have attached to them, but the size seems to vary. Sometimes an Alias will be 1MB. Sometimes a few KB. And for some reason in this case 6MB.
An Alias can have a colored label attached to it while a Symlink cannot. But this wouldn't add a lot of information to the file at all as colored labels don't really do anything except tell the Finder what color to make the text. It would be a single byte at most telling the Finder a number between 0 and 7 if anything.
I can't see what would make a link to another location take up that much space unless it's a lot of filler. So weird.