They do not seem incompatible to me since they talk about different types of 'totality'. The first definition takes 2 sets $X, Y$. While the second definition uses only one set. (It's a binary relation over one set, wikipedia speaks of endorelation)
You could transform the first definition so that it uses one set:
A relation $R \subset X\times X$ is total if it associates to every $a \in X$ at least one $b \in X$; that is
$$\forall a \in X, \exists b \in X: (a,b) \in R$$
However, this is weaker than the second definition. Wikipedia would speak of left-total.
Roughly said:
The first definition demands that from every element in the source at least one relation departs.
While the second definition demands that every element in a set has a connection with every other element in either one, or another direction (or both)
Compare following examples:
In the first picture the relation is left-total from $X$ to $X$. (Every element has at least one arrow departing - C has even two arrows departing). While the (endo)relation is not total as in definition 2. In the second picture it is total as in in definition 2. It also seems to be left-total.
(When a relation is total as in definition 2, it does not have to be left-total. Can you find an example?)
$(\boldsymbol{1})\quad$ We call $\,P(n,k)\,$ k-permutations. Order matters, repetitions not allowed. The number of permutations of the n objects taken k at a time:
$$P(n,k)=n(n-1)...(n-k+1)=\frac{n!}{(n-k)!}$$
So, these are ordered arrangements/selections/choices. We also use $\;_n P_k\;$notation.
$\quad$
$(\boldsymbol{2})\quad$ When we permute all objects we simply call them permutations and write $\,n!$
$\quad$
$(\boldsymbol{3})\quad$ If repetitions are allowed and order matters, we refer to such arrangements as permutations with repetitions or distinguishable permutations:
$${{n}\choose{n_1, n_2, n_3…,n_p}} = \frac {n!}{n_1!\, n_2!\, n_3!…n_p!}$$
$$\quad$$
$(\boldsymbol{4})\quad$ When we have $n^k$ ordered arrangements, replacement allowed -- we call them permutations with replacements or k-tuples.
$$\quad$$
$(\boldsymbol{5})\quad$ When repetitions are not allowed and order doesn't matter, we call such arrangements combinations: ${{n}\choose{k}}\;$ or $\;_n C_k\;$ or $\;C(n,k).\;$ We choose n objects taken k at a time without regard to order. We read it "n choose k" and write:
$${{n}\choose{k}}=\frac{n(n-1)...(n-k+1)}{k!}=\frac{n!}{k!\,(n-k)!}$$
$(\boldsymbol{6})\quad$ And finally, when we deal with unordered arrangements, repetitions allowed -- we call them combinations with repetitions:
$${{n+k-1}\choose{k}}=\frac{(n+k-1)\cdot...\cdot n}{k!}=\frac{(n+k-1)!}{k!\,(n-1)!}$$
Please note it doesn't matter what these are called in German or French since each language has its own rules. An English manual of style is not applicable to other languages and vice versa; likewise you can't replace permutations or combinations with German variations in English. Yet we sometimes have different notations even within one language as authors may have their own preferences in terms of notation and terminology. There's nothing to worry about here.
Despite sounding a little pejorative to me, a German language speaker, it raises a question of whether such usage is really (internationally?) deprecated and considered outdated? -- No. That's more of a speculation on terminology used in other languages by some Wikipedia writers. See their editing history. Do not blindly trust something which is not a hard science in Wikipedia.
Do other languages possibly also name it differently? -- Yes. You can see it in the comments from people of other countries. There should be a lot of subtle examples. Let me make a rough guess based on "googling":
Disposizioni semplici=Variation ohne Wiederholung=l'arrangement=k-permutations
Arranjo com repetição=Variation mit Wiederholung=permutations with replacement.
So we should have been able to say these are just different technical terms -- but no -- it gets more complicated because in German terminology permutations are just a special kind of "variations". -- Yes, to some extent at least. Permutations is a broad term in English. What's more you can view these formulas from different "angles", e.g., combinations being just a special case of distinguishable permutations, permutations being just ordered combinations; and permutations with replacement can be called permutations with repetitions (it might create some confusion!) and so on.
The German flow chart with the German nomenclature? -- I checked it. It's really nice and logical. Quite commendable. I don't see how it may be inferior to any other nomenclature. It is rather on the contrary.
Nomenclatures, notations, and terminology differ from country to country. In biology, any species receives a binomial name (Latin name) and there's no ambiguity across the world about that species. In math we also have universal symbols and notations but they are not so rigid. You can find $cot^{-1}$, $arccot$, $arcctg $ used to denote the same and so forth. You can find in some countries analytic geometry is almost never part of calculus but always part of linear algebra. Sometimes you can find calculus being called mathematical analysis and being confused with analysis or real analysis. You may come across calques (or verbatim translations) of higher algebra, general algebra, etc. You may see how in English we coined words Calc I, II, III, IV as well as precalculus. Things are not clear cut, and there will be variations, just like the difference in meaning the word gift has in English and in German. While the word variation may have very similar meanings in English and German, there will also be differences, maybe subtle differences. And it is exactly the words with minor differences in meaning that cause most of the confusion. People expect them to be the same but they are not. One final example. We have books on vector calculus but it is a bit of a misnomer, as these books are just enhanced versions of Calculus III/IV. And it may have no bearing whatsoever on what might be the case in other languages.
CONCLUSION:
Now we can answer the "title" question: Why are permutations P(n,r) called variations in languages other than English? -- That is simply not the case! While European languages may use math variations in a similar way, the usage will diverge to some extent.
IMPORTANT:
Please note that not only technical terms are quite different from country to country but notations, too, may vary. Thus, in France, Russia, etc. permutations are often denoted $A^{k}_n$, and $C^{k}_n$ is used for combinations, which means the upper and bottom indexes are reversed. It may lead to mistakes in translation.
Best Answer
I agree: there is no rigorous definition of growth. In modern mathematics, growth is something relative and not absolute. So you speak of exponential growth for the function $u$ if $$\lim_{x \to +\infty} \frac{u(x)}{e^{px}}=\ell\neq 0$$ for some $p>0$, or $$0<\limsup_{x \to +\infty} \left| \frac{u(x)}{e^{px}}\right|<+\infty.$$ Similarly, you speak of polynomial growth. In other words, growth understands some comparison class of functions.