Question: Can we use an adverb and a prepositional phrase interchangeably in the following sentences? 

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> A. 
>  (With adverb) She used to reach there on time **daily**.
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> (With phrase) She used to reach there on time **on a daily basis**.
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> B.
>  (With adverb) She used to reach there in a well-prepared manner **daily**.
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> (With phrase) She used to reach there in a well-prepared manner **on a daily basis**.
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Answer: 
Yes, these all are different words with different meanings. There are *some* circumstances where all three might *work*, but that doesn't mean all work in *all* circumstances. 

*Whereas* is much more formal and is used in things like legal documents and formal proofs. It means the same as "given" or "presuming", and is really little more than a preface to some logical statement: "*whereas* A is true, we can conclude B". 

*Whereas* can also be used to contrast two statements in much the same way as "but" or "however", in a more formal way: "Whereas A is true in one case, B is true in another"

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> **Whereas** the plaintiff was given many warnings about the dangers of his product, he cannot now claim he should bear no responsibility to the defendants who were injured by it.
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*Although* is common and generally means *despite* or *regardless of*: "although\* A may be true, it is not relevant to B".

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> **Although** the plaintiff was given many warnings about the dangers of his product, those dangers are inherent to its use and clearly iterated in the user manual, and the defendants should assume full responsibility for the risk.
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*While* is common and generally means *concurrent or included with*: "while A may be true, B is also true".

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> **While** it is true the use of the product is inherently risky, the issue lies in the plaintiff's faulty design, not the way the product was used.
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Again, there is some overlap in many contexts, because each represents similar logic.
Assuming the idea you want to express is that you prefer to get wet over carrying an umbrella; it is raining but *nonetheless* you are not going to carry an umbrella:

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> Although it is raining, I refuse to bring an umbrella. OK
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> Whereas it is raining, I refuse to bring an umbrella. not
>  OK
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> While it is raining, I refuse to bring an umbrella. not a perfectly clear expression of the idea
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In most non-legalistic contexts in contemporary English, **whereas** can be understood as a synonym for **yet** or **to the contrary**:

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> You bring an umbrella whereas|while|yet I do not. OK
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It introduces a clause that runs contrary to the idea expressed by the previous assertion.

In legalistic contexts, **whereas** works like **Since** or **Given the fact that**:

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> Whereas Customer wishes to purchase platinum-plated electrical connectors and Vendor is in the business of providing such connectors, therefore the two parties do hereby agree ...
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