There are a number of ways I think Quicklisp improves on asdf-install. Here are a few:
* Quicklisp centralizes metadata and project archives, so you don't have to rely on a world-writable wiki and 10 random servers on the internet to install a project
* Quicklisp doesn't need any external programs like tar or gzip
* It works nicely on Windows
* There is a level of integration testing before projects are published; it's not much, but it's way better than nothing
* It works with projects that don't go through a formal "release a tarball" process
* It can be installed by loading a single Lisp source file
* It's not named asdf-install, so not confusing people about where asdf stops and asdf-install begins
The main way they do the same thing is at a very high level. I think Quicklisp gets more of the important details right.
and to add to this, they play nicely together, so you can asdf-install a new local version of a package available through quicklisp, and (require 'that-package) will load your newer local version.
* Quicklisp centralizes metadata and project archives, so you don't have to rely on a world-writable wiki and 10 random servers on the internet to install a project
* Quicklisp doesn't need any external programs like tar or gzip
* It works nicely on Windows
* There is a level of integration testing before projects are published; it's not much, but it's way better than nothing
* It works with projects that don't go through a formal "release a tarball" process
* It can be installed by loading a single Lisp source file
* It's not named asdf-install, so not confusing people about where asdf stops and asdf-install begins
The main way they do the same thing is at a very high level. I think Quicklisp gets more of the important details right.