Book vs. T.v Show

I'm reading the first book of the Pretty Little Liars series. The first book is called Pretty Little Liars. The books were made into a t.v. show on abc family, I'm obsessed with the show. I started reading the books because I liked the show so much, but the book is so far pretty different from the show. In the book only like two of the characters are described the same as they are in the show, like with their looks. The personalities of the characters are mostly the same and the plot line is pretty similar.

I don't know if it's different because it has more detail in the book or just the show didn't follow the books that well. I'm only on page 52 so maybe it will get more similar to the show but I've been told that it's completely different in the books. I'm excited that it might be different it will give me more perspectives I think.