Ok Here is your Answer:

Leech->

http://en.wikipedia.org/wiki/Leech
A leech is a person who sucks data, resources or bandwidth away from a network or website in a way that’s considered ethically questionable or shows poor netiquette. This usually means placing a burden on the target without reciprocating something of equal value. Leeching has an additional meaning in the world of torrents, and again in USENET binary newsgroups where being a leech is perfectly acceptable. So what are the differences?
In the wireless world, a leech is someone who steals bandwidth by stationing himself outside a wireless café, for example, so he can use the service without patronizing the café. A neighbor who uses her neighbor’s network without permission is also considered a leech.



http://www.wisegeek.com/in-computing...is-a-leech.htm

Rapidleech->

Rapid Leech is a free server transfer script for use on various popular upload/download sites such as megaupload.com, Rapidshare.com and more than 45 others. The famous Rapidleech script transfers files from Rapidshare, Megaupload, Depositfiles.com, Easy-share.com, etc, via your fast servers connection speed and dumps the file on your server. You may then download these files from your server anytime later.

Rapidleech script has being used by more than 5 million users worldwide and has being installed on more than 2000 servers.

For webmasters, if you have not tried the script before, download and install now and you will see how convenient the script can be. You may also generate income by offering your Rapidleech sites to end-users and earn income from advertising programs. Some webmasters are earning hundreds per day on the advertising program(Google and yahoo Ads) from their Rapidleech sites. Script installation is extremely easy and does not require any database.

For end-users, you may search on our forum for readily available installed scripts on servers worldwide. You may use them but please support these sites by visiting their sponsors or donate in order to keep these sites available.

Source---->
http://www.rapidleech.com/