Even the smallest child posing as a caveman could hear the influence of Spielberg on Goldsmith in this score; It's well documented that Spielberg wanted to work with Goldsmith and vice versa; Spielberg was also the one who dealt with Goldsmith during post-production and I'm sure instructed him on the music and was instrumental in Goldsmith crafting Poltergeist. I'm also positive had Williams have done it, the approach would have been similar. So yes, I do get the impression that there is a similarity in style. The bike ride into the neighborhood is a prime example.
With Spielberg gone on the sequel, the sound for the franchise definitely changed more to Goldsmith pure.
"The Neighborhood" cue is very much Williamesque as well as the cue where the clown makes its first appearance. Other than those examples I'd say the rest of the score is vintage Goldsmith.
Well, it's not like Goldsmith hadn't written bright lyrical passages like that before. Listen to Raggedy Man for instance. I think nearly all Spielberg produced films of that era had a similar sprite to them. Back to the Future, Batteries not Included, and Harry and The Hendersons are other good examples of this.