I am a sound technician. I’m mostly self trained, but give me a situation where you need a sound system setup and to sound good I can handle it easily.
I am not a DJ. I lack that certain something that is required to know the precise timing of when to play what kind of songs, and keep people entertained and dancing.

The difference seems glaringly obvious to me, but I am observing from within. So in my opinion the difference between a sound tech and a dj is this:
A DJ is there to keep people entertained, a sound tech is there to run equipment. Most DJs are sound techs, but not all sound techs are DJs.

Now comes the tricky part, trying to get people to understand which one they want at their function.
If you want someone to adjust audio levels, play a little background music, and otherwise be invisible you can survive with a sound tech.
On the other hand if you want someone to create a lively atmosphere, initiate events, and keep a party going you want a DJ.

Example 1: A church service:
responsibilities:  Adjust audio levels while people speak, create a recording, and maintain equipment.
You want a sound tech

Example2: A Halloween party:
responsibilities: Play a blend of music, keep the energy level in the room up, and be a bit of a personality that keeps the party flowing.
You want a DJ

If you find yourself at an event where the person doesn’t seem to have control over what music is played when, has no music library to select from,
and really has no system for request or special events or dances, chances are he is a sound tech not a DJ. In an emergency he can step in
and try to fill the role of a DJ, but please understand he lacks several things required to host an event as though he were a DJ.

Also an IPod is never a substitution for a DJ. Sure you may have great taste in music, but can your Ipod read a crowd
and know when to start playing faster dances songs to really get the crowd moving or even the opposite, know when to slow things down.

Now I am happy to do sound if you come to me through the proper channels, but I am not a DJ. I can fake it pretty well if I have the
right equipment (oh I don’t know two laptops, a good internet connection, and a list of the precise songs of I’m looking to play).
This being said it is very hard when people come up expecting a DJ not realizing the guy by the sound system is just a sound tech.

RGS out…
Calvsie