What's the difference?

Over the past few months, I have found that many people take pleasure in pointing out the subtle (and more often than not, irrelevant) differences between things. Often they're just trying to be clever so I thought I'd attempt to clear a few up. Please let me know if I'm wrong.

With some of the following pointless information, maybe you can fight the sods with their own weapons...

What's the difference between a tube and a pipe?: A tube is formed continuously (such as an extrusion), whereas a pipe is rolled from sheet material and seamed along its length.
Source: Howard Fulford
What's the difference between a boat and a ship?: The author has seen claims that a ship is greater than x tonnes in displacement of water, but the only conclusive difference found is that a ship has three or more square-rigged masts.
Source: http://www.dictionary.com/
What's the difference between a jig and a fixture?: A jig guides tools relative to the work piece, whereas a fixture holds the work piece.
Source: Ken Gately
What's the difference between a bolt and a screw?: A bolt threads into a nut whereas a screw threads into the material to be fastened.
Source: Tom Oakley
What's the difference between a shaft and an axle?: An axle has wheels.
Source: http://dictionary.reference.com/search?q=axle
What's the difference between sheet and plate metal?: Sheet metal is less than 3 mm thick, plate metal is more.
Source: Tom Oakley
What's the difference between a road and a street?: Strictly, a street is paved whereas a road may not be.
Source: http://www.dictionary.com/
What's the difference between an email address and a website address?: Internet addresses are actually numbers called "IP" (Internet Protocol) addresses. You will sometimes see addresses like http://216.239.59.104/ which in this case is the search engine Google.; Most websites (and email addresses) replace their IP addresses with something easier to read such as a word like http://google.com/; We can do this by using Domain Name Servers (DNS) - when you type google.com a DNS sends you to 216.239.59.104 without you seeing the difference.; The DNS system works on domains - there are top level domains such as .com, .net, .org, .mil, .uk, .au and so on.; Then there are domains such as google.com, yahoo.com and tomoakley.net. Those domains are normally owned by an organisation or individual. Thus every email or web page request sent to tomoakley.net comes to my server.; Now, here's the difference between email and website addresses: when @tomoakley.net is seen, the "@" sign is recognised and a program called a mail server is used to process the email.; When http:// is seen, a webserver is used to process the request as a webpage. Note that http stands for hypertext transfer protocol. It's the language your web browser and my server use to talk to each other.

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