I often saw that the Russians use the adjective "крутой" and "жёсткий" to describe personalities, but I find it hard to understand these words and the difference between them. Here are a couple of examples of sentences with these words:
(1) Луиза Носкова: «У Гурьева крутой характер. И поэтому приходилось приспосабливаться» (Source)
(2) У этих знаков Зодиака самый жесткий характер. (Source)
These words can be also used as adverbs and nouns to talk about personality traits or behavior - круто, жёстко, крутизна, жёсткость.
My impression is that "крутой" and "жёсткий" as personality traits are Russian terms that do not have precise English equivalents.
The definitions of these words in Wiktionary are very vague and are given simply as a list of synonymous words and expressions:
крутой: суровый, упрямый, своевольный
жёсткий: суровый, грубый, не допускающий возражений или колебаний
The word "суровый," listed in the above definitions, is defined in Wiktionary as follows:
суровый: очень строгий, серьёзный
Opening the definition of "строгий," I see that it is defined as follows:
строгий: жёсткий (перен.), суровый
Thus the circle is closed: "жёсткий" is defined via "суровый," then "суровый" is defined via "строгий," and then "строгий" is defined via "жёсткий." An excellent three-move combo to make a poor Japanese student totally confused and disoriented.
I also looked in some other online dictionaries, but could not find anything better than vague definitions similar to what I saw in Wiktionary.
At the same time I strongly feel that native speakers have a very clear idea about these words. For instance, I was amazed to see how artistically one Russian talks about the term "крутизна":
(3) В заключении, я хочу сказать, как лично я понимаю крутизну президента России на международной арене, вне зависимости от личности: 1) Сбили турки российский самолёт – сбить турецкий или нанести ракетный удар по одному из аэродромов на территории Турции; 2) Нанесли удар по российской базе – нанести такой же подлый удар по одной из американских баз на территории Сирии; 3) Убили российских наёмников – убить не меньшее количество американских наёмников в Сирии и так далее… Только в этом случае политик имеет право на крутизну, а страна на уважение. В противном случае, президент страны лох и терпила, играющий по чужим правилам, ведущий страну по тропинке, протоптанной Советским Союзом к пропасти. (Source)
This definition implies that "крутой" is about the ability to deliver a strong response to a hostile action, and the person who is unable to do so is лох и терпила. In view of this definition, Sentence (1) can be rephrased as follows:
(4) Луиза Носкова: «Гурьев - не лох и не терпила. Он умеет пропорционально отвечать. И поэтому приходилось приспосабливаться»
But I am unsure whether my understanding is right.
My question is this: What are the precise meanings of "крутой" and "жёсткий" as personality traits?
I humbly hope that the native speakers of this SE can do better than Wiktionary and can come up with nice explanations addressing the precise meaning of each of these two words. Especially welcome are examples of behavior characterized as "крутой" or "жёсткий," especially those examples to which only one of these two words is applicable. This will help me understand the difference.