I remember Martians in a tunnel with the consistency of bubble wrap. They would capture people from a Midwest area and would put them in a machine that would alter their brain. The machine looked like a satellite dish with a large needle on the end. At the end of the movie 2 kids were looking out their window an so a space saucer taking off.
Both movies include what I'd call a "signature landscape" for the movies, which is a small hill with a road and some fence, the boy sees from his window (e.g. while the UFO lands):
In general, people go over that road, are pulled down through the sand and then manipulated using what appears to be some kind of giant needle. Due to this, the kid learns that alien controlled people can be identified by wounds on their neck.