EconoJets are a type of single-use motor that are designed to have a propellant weight that is low enough so that they don't require a hazmat fee for shipping. That saves money, hence "Econo." They are all 29mm F class motors. Mostly they are small F's because of the low propellent weight. There are 4 different propellent types available. There are several set delays to choose from. They come in 2-packs. They are ready to go straight out of the package. I like these for Estes PSII kits, like the Leviathan, on small fields.
EconoMax are like EconoJets, but they use a new powerful propellant and other tricks to pack the most power into the small package, hence "Max." AFAIK, there are only 2 types so far --- 24mm F44 and 29mm G74. I have not used them.
24mm E20 motors are packaged and used just like Econo motors, but I don't think they are branded as EconoJets.
Then there are a bunch of Motors simply labeled Single Use that I do not think have any kind of special branding. They are mostly 29mm F and G motors. They require Hazmat shipping, so they are not "Econo." They are in single packaging, not 2-packs. There is a large variety of propellent tyes, longer burns, faster burns, and set delays. These are all ready to go right out of the package.
DMS motors are the Disposable Motor System. These are single use, hence "disposable." But they are not ready to go straight out of the package. You need to drill the delay to whatever you want, and add the amount of ejection charge powder you want. This lets you set the timing and strength of the ejection charge. There are lots of propellent types to choose from. These are not limited to 29mm or F or G motors. I think they go all the way up to 75mm L motors. They keep adding more and more of these.
Ive never used LMS, but I think it stands for Loadable Motor System. I think you basically have to put this motor together like a reload, but the case is disposable, hence "Loadable", not "reloadable."
RMS is the Reloadable Motor System. I don't have any experience with these, but this is where you buy the casing and other reusable hardware separately, and then you buy the RMS motor reload with the fuel grains, delay grains, ejection charge, and some disposable parts to load into the hardware.
I hope that helps.