1. Style
In writing, style refers to the manner in which a writer chooses to use his or her language to express meaning in a given context. In academic writing, the writer aims to adapt language according to the audience and the situation, written in such a manner with a striving to attain high readability; the text being articulate and accurate.

2.Formal writing
The Foreign Office said that it was doing everything in its power and liaising with Pakistani authorities through consular officials. "We are in touch with the family and providing every support we can," a spokesman said. "It would not be responsible of me to say too much in public about what is happening in the investigation." Pakistani police, who earlier suggested that the affair would be over within 24 hours, now appear less confident. They say that they were still making significant progress in tracking down the kidnappers, who struck as Raja Naqqash Saeed, 28, Sahil’s father, was loading suitcases into a taxi outside the family home in Jhelum, Punjab, ready for the flight home. The raiders subjected the family to up to six hours of torture before snatching the youngster and demanding a £100,000 ransom.
(http://www.timesonline.co.uk/tol/news/uk/crime/article7050922.ece)

Tentative language; "...now appear less confident."
Formal language, for example subjected.
No contractions
Relative clauses, for example "Pakistani police, who...".
Long and complex sentences.

Informal writing
I was also lucky enough to receive the skirt with red lips, which I plan to somehow incorporate into a creepy nurse/Richard Prince outfit.Oh, life. Oh, people! You are very good to me, and I am lucky. One day I will be saying to my grandchildren, "You know, I once had a blog, which is like those hologram things you kids have now, but it was on a big cubic device. And some people kinda got a kick out of it, and I sometimes got things like skirts from Prada." And they'll be like "LOL OK TIME FOR BED, BUBBE."
(http://tavi-thenewgirlintown.blogspot.com/)

Colloquial language such as kids, kinda, creepy, got things
Contraction; they'll
Colloquial expression; "And they'll be like..."
Acronym; LOL

3.Formal
Alice in Wonderland was written in1865 by the English author Charles Lutwidge Dodgson, published under the pseudonym Lewis Carroll. The book was well received and the first print run of 2,000 was quickly sold out. It has never been out of print, has been translated into 125 languages and has over the years captivated children as well as adults worldwide. Although well renowned intellectuals such as Queen Victoria and Oscar Wilde both took much pleasure in reading Alice in Wonderland, it was also made an object of ridicule for being bizarre and unpredictable.
Informal
Alice in Wonderland was written in1865 by Charles Lutwidge Dodgson but published under the name Lewis Carroll. People liked the book and the first print run of 2,000 sold out in no time. It's never been outta print, has been translated into 125 languages and has fascinated children and adults all over the world. Even if famous intellectual people like Queen Victoria and Oscar Wilde were really into the whole Alice in Wonderland thing, t'was also made fun of because t'was just weird and unpredictable.