Actually there is a more obvious difference in spelling too but due to political correctness is better not to mention it. Rom is short for Romania while the Rrom are the majority gypsy clan in Central Europe. However, in the early 1990's when the emigration from Central to the Western Europe started, the gypsies realised the spelling confusion will be in their favor. So they insisted of spelling their name as "Rom" instead of "Rrom".
Now you have learned something today

PS: Oh, I see AI is more open nowadays...