Just totally different eras, and Rice's third year was in a shortened season due to labor issues. Let's compare their second years in the league.
In 1986, his second year, Rice had 86 receptions, 1570 yards, and 15 TDs. He was second in the league in receptions, first in yards, and first in TDs. By comparison, in Green's second year, he had 97 receptions, 1350 yards, and 11 TDs. He was 7th in the league in receptions, 10th in yards, and tied for 4th in TDs.
In 1986, only 7 players had 80 or more receptions (0 had 100); 16 players had 1000 yards (1, Rice, had 1500); 7 had 10 or more TDs. In 2012, 17 players had more than 80 receptions (6 had 100), 20 had 1000 yards (3 had more than 1500), and 10 had 10 or more TDs.
In Rice's third year, he set an NFL record for touchdowns with 22 in a 12 game season.
The insane thing about Rice when comparing him to someone like AJ Green, a top-10 or so receiver in the current era, is exactly that Rice put up better statistics in an era when the average receiving stats were substantially lower across the board.