What is the difference between "It is necessary for him to do something" and "It is necessary that he do something"?

It is necessary for him to do something.
It is necessary that he do something.

I know the second one is subjunctive and I know that it is used for command, demand, etc.

I want to know what difference does it make in the meaning?

Is subjunctive used in spoken language?

Examples:

It is necessary for Tom to arrive at 5.
It is necessary that Tom arrive at 5.

Solution 1:

The difference between It is necessary for him to do something and It is necessary that he do something is one of formality, not meaning.

The subjunctive he do in the second sentence is one of the six surviving uses identified by Garner, in Modern American Usage (p780): namely, statements of necessity. He cites these examples:

It's necessary that they be there.

His entrance into the military made it necessary that he use the birth-certificate version of his name.

It will be necessary that he or she have a solid understanding of school finances.

Garner states that the use of the subjunctive for statements of necessity is most common in writing, and is of the opinion that the usage is "worth keeping".

Peters in The Cambridge Guide to English Usage (p520) lists necessary as one of the adjectives which "introduce mandative clauses that typically take the subjunctive". She states:

The mandative subjunctive is regularly used in North American English ... .

In British English the mandative subjunctive declined during C20, perhaps because of Fowler's (1926) general onslaught on the subjunctive, on the basis that it was either misused or pretentious. ... British grammarians since then have tended to say that it's primarily associated with formal style.

Peters notes that "British writers have expressed the mandative by means of the modal verb 'should'".

I would add that it is also not unusual, in British English at least, to use the indicative. Here are some Google counter-examples to Garner's mandative subjunctives above:

So it's necessary that they are self-sufficient.

It's necessary that he uses that pen, otherwise ... .

It's necessary that he has his infamously snazzy "Pirates of the Caribbean" Jack Sparrow suit at the ready.