Definitely some good feeback so far. I will give my 2cents about the difference, if it helps.
First, we only do residential landscape work, so a landsape designers is typically more than sufficient for the work we do. I would consider using a landscape architect if the client had a really large estate property, could afford the landscape architect (which are generally 3-4x more expensive than a good landscape designer) and the work was complicated enough that it would be really helpful to have the more knowledge that an LA would have. But that's rarely the case for what we do, so we don't often work with LAs.
If your goal is to make more money, a good LA will always make more than a good landscape designer. As good as some landscape designers are, none of them make what I would consider good money.
But I personally would enjoy being a landscape designer more. I think they are generally more creative. They have a better handle on plant materials. They have a better handle on current construction methods, materials being used, what residential clients like to see, and are able to work within a client's budget more easily than a LA would. I have done several projects over the years that were designed by and sometimes even managed by (that is to say, they were looking over our shoulder as we did the work) a LA. I have to say, those were about the most annoying jobs we ever did. The LA comes into it thinking they know everything, second guessing our methods, and then only when I sit down and explain why we do things a certain way do they finally understand and allow us to continue. They don't generally have a good handle on which variety of pavers are most popular, which plantings do well and have really been successful in our area, and often tend to design things that are next to impossible to really build. Then when you approach them with a question like, "How, exactly were you expecting this to be built??" they give you attitude, like, "What? You've never built one of those before? Maye I have the wrong company then! I would have thought you had more experience in this area."
Anyway, enough of me dogging on LAs, just my experience with them hasn't been that great. I'm sure on big estates and big commercial properties they end up doing some great work. I just find them to usually be a little less informed and less down to earth than the local area designers are. But they definitely can handle bigger, more complicated projects and make a lot more money.
A guy I know locally who is a landscape designer came to one of our meetings recently, wanting to introduce himself and hoping we'd send him some design work. At the meeting, he explained that he had been in LA school but dropped out and decided to just become a landscape designer instead. The reason why, he explained, is because as he looked through the entire 4-year program, there was only one class on plant ID and horticulture. All the rest of the courses were not related to plants. And to him, this was the most important part of designing landscapes and his passion was really for plants. So he switched. I didn't know it was like that. But if that's true, that is telling. Check out the program you're wanting to attend and see if that's the case.
Best of luck making your decision.