But there is a connection.

Intelligent Design (ID), being essentially anti-evolutionism, is half of an argument for creationism.

Basic scientific arguments go something like this:

  1. You are wrong.
  2. I am right.

Or, in more detail:

  1. Your model does a poor job at explaining the data.
  2. My model does a better job at explaining the data.

So one might argue for creationism as follows:

  1. Your model of evolution (by random mutation and natural selection) does a poor job at explaining the data (life in all its complexity).
  2. My model of creationism (old-earth, young-earth, whatever) does a better job at explaining the data.

Anti-evolutionism is the first half of that argument.

So ID is not creationism. But it is half an argument for creationism, which is why creationists tend to like ID.

Incidentally, as long as ID remains as just half an argument, I don't think it will get very far. People will always believe something rather than nothing. If you tell people that the thing they believe is wrong, they will continue to believe it regardless, until you provide a solid alternative. If you decide you want to leave your current town, you don't just pack up and get in the car, but you find somewhere else to live and then you pack up and leave. ID says you should leave your current town, but it doesn't show you somewhere better to live, so I don't think many people will listen.