Things were different in 1912. There was no such thing as the "Bambino Curse". The Red Sox win in the 1912 World Series was their second, as they became the third team (Cubs and Athletics) to win a second World Series title. The Red Sox would win three more titles, in 1915, 1916 and 1918 before going on the historic drought. The Giants won the second ever World Series in 1905 (after they refused to play in the 1904 fall classic), but were beaten in 1911-1913, including in the famous "Snodgrass muff" Series.
Many things can be compared when discussing these two unfortunate incidents. The amount of years that had gone by since the Red Sox won the World Series was as responsible for Buckner's tough times afterwards as the error itself. After 1912, the Giants would win the World Series in 1921 and 1922. While Snodgrass was no longer playing, having been released by the Giants in 1915 and hanging it up after playing for the Boston Braves in 1916, he got to see his former team win a WS within a reasonable time. Furthermore, the Giants had won a World Series title eight years prior 1912. The Red Sox in 1986 had waited 68 years since their last title and would wait another 18 before finally capturing the title in 2004.
Perhaps comparing the two events is unfair. Truthfully, Buckner's error came with the score tied in the bottom of the 10th inning. Snodgrass's error allowed the tying run to reach base in the deciding game of the World Series. The good thing about it is that both players have been vindicated when their respective teams won the World Series. Mickey Owen, the Brooklyn Dodgers catcher that dropped Tommy Henrich's swinging strike three against Hugh Casey in 1941, was similar in the fact that his gaff perhaps cost the Dodgers a chance to win the World Series that season. The passed ball happened in game 4 of the series the Yankees would take in five games.
Snodgrass' 1912 teammate, Fred Merkle, had to live with his mistake the rest of his playing career though he managed to play in 5 World Series with the Giants, Robins and Cubs. Merkle reportedly cost the Giants the 1908 NL Pennant by failing to touch second base before scoring a crucial run. Leon Durham's missed ground ball in 1984 led to the Padres rallying from a 2-0 series deficit to get to the World Series. In a very controversial call in 2005, White Sox catcher AJ Pierzynski reached first base on a passed ball by Angels catcher Josh Paul. That happened as Pierzynski struck out for what was to be the third out of the bottom of the 9th inning of game 2 of the ALCS with the score tied 1-1. Though the Angels won in 2002, neither Durham or Paul can say "at least their teams won a World Series later on".