I must disagree. Their styles are nothing alike. Campbell style is extremely influenced by the likes of Wally Wood and Jack Davis, while Howard is heavily influenced by the influx of Japanese anime and manga. Howard's work has nothing on Campbell.
I can see where one might compare the two, but I can see a great difference in both artists as well. Either way, I enjoy the work of both.
he kinda draws like j.scott campbell creator of danger girl