Before the Russians got involved in this region, very late in the EU4 - era, Bessarabia was the traditional name of the southern plains region and only later did it become the name of the eastern region represented by Bender on the screenshot above
Wikipedia has a pretty good map of how the meaning of the names drifted:
http://upload.wikimedia.org/wikipedia/commons/6/6a/Partitions_of_Moldavia.jpg
The names there are half-English and half-Romanian and mixed up on the maps... Moldova(Ro) - Moldavia(En) and note that this name, Moldavia, for the map's Western region is wrong in English, because "Moldavia" refers only to the historic medieval country, while Moldova(region of Romania) and Rep. Moldova are the correct names to use in English(I had no idea why it's so, because Romanians and Moldovans use only "Moldova" for all those things, but it's so). Basarabia(Ro) - Bessarabia(En), Buceag(Ro) - Budjak(En)(historically this province was called Basarabia, like you said), Bucovina(Ro) - Bukovina(En) *note that this name is made-up by the Austrians, who took the northern part of Moldavia, not even Ukrainians use it for that part of Moldavia(only the Habsburgs and current-day dumb Romanians *I have no idea why some of my countrymen are so eager-beaver on adopting foreign names for their regions, it would be like people from Rep. Moldova would call themselves "Bessarabians" instead of Moldovans, just because the Russians nicknamed the whole region Bessarabia, and not just the south, when they took it over).