Why Germany is known in world in a diverse way?
I believe this has to do with different nature of encountering Germans when it came to other nations.
Germany has a more important strategic location than France does. France is in the Western most reach of the Continent while Germany is in the center and had more dealings with Slavs in the East, Latins in the South, Nordics in the North and Frisian/Dutch in the West. They have also traditionally dominated/or played an very important role in global affairs since ancient times. (This does not imply that France did not play a similar role).
France was a nation for most of the time ever since Franks captured Gaul but Germans were separated into small states for most part of their history until the unification of 1871, which ironically also materialized after defeating the French in Franco-Prussian war of 1870. Which is why different nations came to know them by names of different factions or tribes.
Etymology of different names for Germans
France was ruled by Franks who also conquered Other German tribes which also included a very large tribe named Alemanni who settled in Eastern Direction of Frankish realm, along the Swiss border and beyond, precisely the Alsace Lorraine region. Thus French came to know the people East of the Rhine as Allemand.
Italians call the Germans Tedeschi but it derives from Theodiscus which shares the same root as original word Deutsch. I thought it had something to do with Teutonic but that's not the case.
Dutch are Germanic people themselves and among all other Germanic languages, Dutch is closest to German. Therefore they use Duitsers which is very close to original word Deutsch.
The Slavic name Niemecki (And other variants) for Germans comes from name of yet another Germanic tribe, the Nemetes who lived in region of Lake Constance. Luboš Motl has pointed out another theory for this word which I quote:
"The Slavic word (e.g. in Czech: Němec, Německo - German, Germany) has
the root meaning "mute" - which is an exaggeration of the fact that
they can't speak our (Slavic) language".
But I am more inclined to believe the Nemetes theory because the theory presented by Lubos is suspiciously similar to how Arabs used to mock Non-Arabs by calling them Ajam which basically means mute. Nevertheless, Luboš Motl's theory has more evidence than the one I presented does but well someone had to present it.
The Scandinavian name Tysk for Germans is derived from old Norse word þýzkr which means the People. German word Deutsch is also derived from the root word þeudō which also means the people. Which is why Nordics call the Germans Tysk and Germany Tyskland.
Found a very amusing countryball meme describing the situation on German Stackexchange thanks to Peter: