Into (and similarly onto) uses direction, whereas in and on don't. Example: A dog is running in the park (he is already in the park, now he is running). A dog is running into the park (he was running outside the park, now he has run through the gate and is running in the park) The child is jumping on the bed (he is already on the bed, now he is jumping up and down). The child is jumping onto the bed (he was standing on the floor, he jumped from the floor to the bed).

There is no difference in the meaning. "In" can be an abbreviation of "inside" or "into" Example:" I am in the car" "I went into the car"