This is a good question brought up time and time again in class or the workplace, conferences, and manuscripts. I have heard instructional design programs called:
Instructional Technology
Instructional Design
Educational Technology
Educational Design
Learning Sciences
and there are many more but these are the common ones.
The reason, in my opinion, that there are so many different names has to do with the fact that we borrow from so many different fields, so each program and/or person has a slightly different focus on one or more of those fields. Thus you have instructional design programs that focus more heavily on design, programming, K-12, corporate, assessment, analysis, etc. Overall however, we are all linked by one thing: ADDIE (except for some of the learning science programs which have more of an ed psych base and do not use any form of ADDIE although I believe this is changing).
I believe all of these different names are not helping our field. In fact, they are hurting us and the field. I believe our field needs a common name with a solid operational understanding of what it is. One of the first things that happens during re-engineering of a company is ensuring that everyone understands their basic terminology because its a problem when the executives think they are saying one thing but others understand it differently. We cant even agree what to call ourselves better yet define our field. We have groups who define our competencies and they are all very similar yet we still choose different names. This confuses potential employers who might be looking for instructional designers but are confused that someone has a learning science degree. While these programs have slight differences we need to put them aside for the reasons I have described. We need to make it clear what our students do and what all students in our field do. I am not saying we need to only train designers or anything like that, but we need to make clear all the roles we can and do play.