Question: What is the difference between *to allege* and *to claim*? Can I use them interchangeably? Or perhaps I can only *allege* something illegal?

For example, from CNET:

> 
> Over the past several months, the two companies have been embroiled in
>  litigation in which Apple **alleges** that Samsung illegally copied
>  technology and design aspects of the iPad to create the Galaxy Tab.
> 
> 
> 

If I replace *alleges* with *claims*, does it change the meaning at all?

Answer: 
[*Alleges*](http://www.oxfordadvancedlearnersdictionary.com/dictionary/allege) means:

> 
> to state something as a fact but without giving proof
> 
> 
> 

It is very similar to *claims*, but it is used in situations where there is a legal accusation which has not yet been resolved. For example, Apple here *alleges* Samsung copied technology. This may or may not be true, but in any case it is a legal claim. 

You could use *claims*, but it wouldn't have the same connotations.
The only difference is one of diction. "Alleges" is in a much higher register than "claims." "Alleges" is also preferred in legal contexts.