Ok, since people truly and actually often ask me about what the differences are between curl and Wget, it might be suitable to throw in my garbage here and state the main differences as I see them. Please consider my bias towards curl since after all, curl is my baby – but I have contributed code to Wget as well.

curl

• Features and is powered by libcurl -a cross-platform library with a stable API that can be used by each and everyone. This difference is major since it creates a completely different attitude on how to do things internally. It is also slightly harder to make a library than a “mere” command line tool.
• Pipes. curl is more in the traditional unix-style, it sends more stuff to stdout, and reads more from stdin in a “everything is a pipe” manner.
• Return codes. curl returns a range of defined and documented return codes for various (error) situations.
• Single shot. curl is bascially made to do single-shot transfers of data.It transfers just the URLs that
  the user specifies, and does not contain any recursive downloading logic or any sort of HTML parser.
• More protocols. curl supports FTP, FTPS, HTTP, HTTPS, SCP, SFTP, TFTP, TELNET, DICT, LDAP, LDAPS and FILE at the time of this writing. Wget supports HTTP, HTTPS and FTP.
• More portable. Ironically curl builds and runs on lots of more platforms than wget, in spite of their attempts to keep things conservative. For example, VMS, OS/400, TPF and other more “exotic” platforms that aren’t straight-forward unix clones.
• More SSL libraries and SSL support. curl can be built with one out of four different SSL/TLS libraries, and it offers more control and wider support for protocol details.
• curl (or rather libcurl) supports more HTTP authentication methods, and especially when you try over HTTP proxies.

wget

• Wget is command line only. There’s no lib or anything. Personally I’ve always disliked the project doesn’t provide a man page as they stand in the GNU side of this and consider “info” pages to be the superior way to document things like this. I strongly disagree.
• Recursive! Wget’s major strong side compared to curl is its ability to download recursively, or even just download everything that is referred to from a remote resource, be it a HTML page or a FTP directory listing.
• Older. Wget has traces back to 1995, while curl can be tracked back no longer than 1997.
• Less developer activity. While this can be debated, I consider three metrics here: mailing list activity, source code commit frequency and release frequency. Anyone following these two projects can see that the curl project has a lot higher pace in all these areas, and it has indeed been so for several years.
• HTTP 1.0. Wget still does its HTTP operations using HTTP 1.0, and while that is still working remarkably fine and hardly ever is troublesome to the end-users, it is still a fact. curl has done HTTP 1.1 since March 2001 (while still offering optional 1.0 requests).
• GPL. Wget is 100% GPL v2, which I believe is going v3 really soon when they release their next release. curl is MIT licensed.
• GNU. Wget is part of the GNU project and all copyrights are assigned to them etc. The curl project is entirely stand-alone and independent with no organization parenting at all.

This turned out to be a long post and it might in fact be usable to save for the future, so I’m also posting this as a more permanent doc on my site on this URL: http://daniel.haxx.se/docs/curl-vs-wget.html. So possible updates will be done there. Do let me know if you have further evident differences or if you disagree with me on details here!