xfeed,
chiglet has given you the correct de-code of the 2 abbreviations. To go a little further....
Under ICAO rules, IFR aircraft flying Easterly Tracks (000° to 179°) fly at Odd thousands of feet, and aircraft flying Westerly Tracks (180° to 359°) fly at Even thousands of feet. This means 2000 feet vertical separation between same direction traffic, and 1000 feet vertical separation between opposite direction traffic. In recognition of reduced Altimeter accuracy at the higher levels above 29000 feet, this vertical separation is doubled to 4000 feet (same direction) and 2000 feet (opposite direction) respectively. Only Odd levels are used after F/L 290, e.g. 310, 350, 390 etc. for Westerly traffic, and 330, 370, 410 etc. for Easterly traffic.
Later generation altimeters of much improved fidelity have made possible the implementation of Reduced Vertical Separation Minima (RVSM) in some states, where essentially, the 4000/2000 separation is dropped above F/L 290, and the standard 2000/1000 separation is extended from F/L 290 to F/L 410, i.e. 300, 320, 340, 360, 380, and 400 are all useable Flight Levels for appropriately equipped and approved aircraft. Above F/L 410, ICAO separation rules again.
To answer the last part of your question, NO, RVSM is not universal. Some states use it fully, some use only ICAO, and some use a mixture of both in different airspace regions. And then, some states, like China, still use Metric Altimetry, with their own separation standards.
There's more to be said, but I think that that covers the basics.
Regards,
Old Smokey