[Wolfstar]

What is the difference between a press conference and a press availability?

Primarily one of duration and subject matter. Personally, I think all this differentiation is silly, but anyway, there are three types. A press gaggle takes place anywhere other than in the formal setting of the WH media room, and is called on relatively short notice. Typically, gaggles occur on AF1 while the president is travelling.

A press availability is when some dignitary is visiting with the president. After private discussions, both will make themselves available for a few questions from the media. (Usually jointly, but not always.) Usually each leader will answer only two or three questions at these availabilties, rather than the more wide-ranging questions asked at formal press conferences.

The latter are just that: formal conferences in which the president (on occasion, jointly with an A-list leader like Tony Blair) takes a wide range of questions from the media over a relatively long period of time -- as much as 45 minutes to an hour, but rarely longer.

[snugs]

Right we just call them press conferences and the press are told before they begin the intention of them so I suppose similar to yours but we just call them the same name, though sometimes we will use the term full or formal press conference to indicate that it will last for about 30 mins or longer but we tend not to have many of that length but a lot of the shorter.

Though IMHO some of them are no more than press statements because very often they refuse to take questions or only very specific ones.