As far as I can see, the only difference is that one sentence uses 'youth' and one sentence uses 'young man'. A youth is younger than a young man. We would call someone a youth when they are too old to be called a child but are not yet adult - mid to late teens. A young man is an adult. The sentences have no grammatical differences. They are grammatically correct. 'Become' would be a more precise choice than 'be'. Did you intend to write 'thirty' rather than 'thirsty'?

I would argue that the intial clause framing the future event as thirty years hence, combined with an adjective such as "precocious" almost removes the need to refer to him as a "youth" or "young man". You could get away with "this precocious individual", frankly. As it has a slightly tautological feel, in my opinion. -thirty years later -precocious -young/youth That said, B sounds better than A. But perhaps the sentence is a little over engineered, feels a bit like you threw a thesaurus at it. I don't want to criticize it too heavily, I've read a lot worse written by fellow Englishman. It almost feels like you are showing off, though 😂 I love the word precocious, I actually used it a couple of days ago, though it was very tongue and cheek! It doesn't see a whole lot of use in common parlance.

Hi Caxio, I agree with the descriptions below but I would add a couple of details. Youth can mean young man but it is often used in a negative way: "That youth over there is making so much noise" If we compare that with your example we can assume that he is a noble and good person, considering that fact that he is about to become the president. So using "youth" sounds odd. Compare: "He is a lovely youth" - This sounds awkward because of the usual negative meaning of the noun youth "He is a lovely young man" - Sounds much more natural I would also like to add that youth is also commonly used to describe the quality of being young or the period of your life in which you are young: "She was a talented artist in her youth"

My first concern is the error using the word "thirsty". "Thirsty" is a descriptive word indicating a need to wet one's mouth, or satiate a desire to drink liquids. I believe you meant to use the written word for the number "30", which is "thirty". Secondly, I agree with the other answer provided by someone else earlier. The word "youth" is indicative of a child, as opposed to "young man" which implies that he is either of legal age, or he soon will be of legal age. Between the two options, I would choose to use option 1B.