From the 1940's thru about 1979 most of the names you mention identify trailer lengths and sometimes floorplans within a given length (ex. Caravanner, Flying Could, and Safari were all 22' models in the later 1950's). See here
for more infomation on names vs. lengths. Starting in the late 1950's, and continuing at least into the early 1970's, I believe that adding "International" and sometimes "Land Yacht" specified trim levels for a given model. From the late 1950's thru the late 1960's an International was the top of the line, most "self contained" trailer meant for international travel (at least initially). Land Yacht was the intermediate trim level at one time, but it may have become the base trim level in later years. I think that initially, trailers that were neither "Internationals" or "Land Yachts, were the base models. Starting in the early 1970's a new top of the line trim level was added, the Excella, with an even higher trim level the Excella 500 also added. I think this trim level may have only been available on the 31' models.
Now all of this changed beginning about 1980 (when coincidentaly THOR bought Airstream from Beatrice Foods), when specific names were abolished for the various trailer lengths. Instead from that point forward, the names speficied trim levels only, with the following progression from lowest to highest: Sovereign
, International, Excella (including Excella 1000), and Limited, again with Excella 1000 and Limited generally reserved for only the longest models (generally 31'+). Some years all of these trim levels were available and some were only down to a couple of trim levels, as Sovereign
and International eventually went away.
All of this again changed in the late 1990's when the the lower cost "Safari" line was introduced, the "Excella" line became the new "Classic" line, and an intermediate line initially called the "International ", but quickly changed to be the "ultra modern" "International CCD" (or just "CCD" for designer Christopher C. Deam) line came to signify different trim levels, often with different floor plans as well. You can still get a "Limited" trim level upgrade on the "Classic" trailers, so I guess that remains the true top-of-the-line.
I hope this helps.