Of course there's a difference since The Hobbit (the book) is made for children. But the style of the movies is basically the same. Jackson even added the retarded love story to The Hobbit.
I feel like The Hobbit movies are like light versions of the Lord of the Rings.

The Hobbit might be a children book, but I don't think the movies are children films. They have tried to copy the tone from Lord of the Rings - certainly with The Desolation of Smaug. However, the story just isn't as epic, and there are just too not enough plot for three movies. The biggest problem for me is probably the characters though. Bilbo is boring, you never really get to know the dwarfs (except Thorin), and Gandalf and Gollum don't have a lot of screentime. Everything was just better in The Lord of the Rings. Even the special effects. I don't think The Hobbit movies are bad, just a lot worse than Lord of the Rings.