Karl Malone was listed throughout his NBA career at 6'9, 250-256 lbs. I saw him play at Arco mid-late 80's several times, including his rookie season. He was an incredibly chiseled basketball player who would glide down the court effortlessly. The fact that he had John Stockton was no doubt a big key to his overall success, but Malone also worked extremely hard to improve his game each season.
There are definite similarities between him as a very young player and Jason Thompson who at 21 years old 6'11, 250 lbs. is at least a lot more buffed than a super skinny Kevin Garnett when he came into the NBA right out of high school. I'm not over-selling rookie JT at this point, only saying he has interesting multiple skills, a solid well defined NBA body, and tremendous NBA potential. On the other hand, Donte Green is a rather raw teenager, playing one year of college hoops, a SF talented outside scorer (at least this past summer league), with a TONS to learn and grow before he will ever shine at the NBA level. Both JT and Greene could be big stars in the league one day, but I'd put a bigger bet on JT, and IF they both hit stardom JT probably gets there faster.