Will my Insurance Cover Invisalign?

It would be wise to contact the insurance company first, but most of the time they don't ask what tools will be used, just the service (in this case, orthodontics). If you have an ortho benefit, then you have a benefit.
Contacting the insurance company MAY get them to change this stance, as they may not have considered it before. Remember, the goal of any insurance company is to NOT pay out money if they can help it. The less specific you can be, the more likely you will have a benefit.

Some insurance companies do cover Invisalign to some degree, it depends on which plan you have, your available benefits, sometimes your age has a factor, etc. You can call you insurance company directly and get an EOB (Explanation of Benefits) which will outline all of the things your insurance covers and to what degree (or you can just call them to ask them if they will cover invisalign). 
Just a quick note on the space maintainer, it does exactly what it's name suggests! It maintains a space in the mouth (so that teeth do not shift into or around the space). Often times a space maintainer is done to hold a space open for a future implant. Hope this helps!

Thank you for your question. Absolutely, Invisalign can be and often is covered by the insurance. It all depends on the plan your employer purchased for you.