If asked to submit both a shorter and longer abstract, is it possible just to send a shorter one that meets both word limits? I saw the following abstract submission guidelines:


  
  Please submit a 500-word text abstract for technical review purposes that is suitable for publication. Accepted abstracts may be published
  with the printed Technical Program for distribution at the meeting.
  Please also submit a 300-word text abstract suitable for early release. If accepted, this abstract text will be published prior to
  the meeting in the online or printed programs promoting the conference
  


My question is, how close to the prescribed word count do you have to be? Would it be possible to send one abstract for both requirements?
It is possible, but you would not want to do that.

Apparently, these are the guidelines for some sort of conference. Usually, you send in a preliminary abstract, then you get a message back that they will accept your permission within a certain deadline. Now you can write and hand in your article.

If you haven't finished your article in time for the abstract submission deadline, you basically have to write an abstract first. But after you have written your article there are most likely changes that need to be addressed in the abstract, which is why you get more words for the final abstract to amend your early release abstract that will probably be available on the website of the conference.