"Eclipse" is just the common marketing name that model line of brushes. "HP-CS" and "Eclipse-CS" are the same brush: "Eclipse HP-CS" is the proper full name, but users and vendors shorten that to "Eclipse CS" or "HP-CS" according to arbitrary preference. Japanese import versions have different packaging, and aren't covered under local service warranties outside Japan (i.e. you'd have to send it back to Japan for warranty service instead of the US office), but the actual hardware is the exact same brush off the exact same assembly line.
The High Performance C Plus (HP-C+ for short) is a higher end model (between Eclipse and Micron). It's designed more specifically for detail work than the Eclipses (they can both be used as all-rounders, they just have different biases). The nozzle structure is different: more precises, but possibly fussier to disassemble and clean for a beginner, and it has an integrated MAC air valve for making fine adjustments to air pressure without taking your hand or attention off the brush.
It's (on paper: I've never used one myself) a more capable brush than the Eclipse in some areas, but not as much of an ideal beginner's brush, so a lot of people end up starting out with an Eclipse, then skipping right over the "High Performance" line altogether and buying a Micron when it comes time to upgrade. However if you don't anticipate being able to afford a Micron (not just to buy one: they can cost a lot to maintain as well), or feel confident jumping in closer to the deep end learning-curve wise, then it might be a better investment than an Eclipse. Maybe: like I say, I haven't used one.
I STRONGLY second what others have advised: take Nada up on his offer to try out his brushes before making a purchasing decision, as this will settle A LOT of questions (including many you won't even know existed) about what you want in your own brushes. This could stand to save you a lot of fuss and expense both short term and long term.
