Although these are two different verbs, in spoken English the meaning would be the same. There are slight nuances in meaning but not enough to worry about - it all depends on who was saying it.
Your two examples depend on the speaker =
1. Is the speaker a child, a medical student or a psychiatric patient?
2. Is the speaker a high school pupil or someone near to selecting their options at medical school? (To become something/someone suggests prior knowledge of to how to do so and an acceptance of your own abilities to do it).
Not too sure that this is of any help - maybe other members can be of more help.
Hi - just have a good laugh about that famous mistake of Germans learning English: "Waiter, when shall I become a beefsteak?" Or alternatively: "Waiter, when shall I be a beefsteak?" Obviously, there is a difference.
Can we say in this sentence someone is referring to what he wants to become in future.
Yes. "to be", as you know, is an infinitive and infinitives express an event as being unactualized. It's the infintive that tells us you are not yet a consultant; Cf. I can be a consultant; I will be a consultant; I should be a consultant.
Originally Posted by rajan
I want to become a consultant.
Can we say someone has not yet become consultant, he/she is under training. Once the process gets completed, he will become consultant.
Yes. "to become" is also an infinitive. The difference between "be" and "become" is semantics. The latter houses the meanings 'change', 'turn'. There's a process involved; e.g., I can become a consultant; I will become a consultant; I should become a consultant.