Key difference: The HeartGold and SoulSilver are role playing video games for the Nintendo DS based on the Pokémon franchise. They were released as a pair in 2009 in Japan. The games were released to North America, Australia, and Europe in March 2010. The player will encounter Kimono Girls throughout the game. After battling all of them in a row, the player will be allowed to encounter a legendary bird specific: Ho-Oh in HeartGold, and Lugia in SoulSilver.

The HeartGold and SoulSilver are role playing video games for the Nintendo DS based on the Pokémon franchise. They were released as a pair in 2009 in Japan. The games were released to North America, Australia, and Europe in March 2010. Essentially, they are remake of the games Gold and Silver, which were released in 1999. However, the new games include enhanced gameplay with many additional new features. The aim of the game director, Shigeki Morimoto was to keep the game true in respect for previous fans, while making it feel like a new game to the newer recent fans.

The game starts from a town named New Bank Town where the player is a new trainer and has to select their first Pokémon. The player must then capture and raise Pokémon and complete a catalogue of Pokémon called a Pokédex. The goal of the game is to become the best trainer in Johto and Kanto by defeating eight Gym Leaders in Johto for Gym Badges, challenging the best trainers in the region known as the Elite Four and the Champion, then defeating the eight Gym Leaders in the Kanto region and eventually facing off against the game's final boss, Red on top of Mt. Silver.

Throughout the game, the player will also battle against members of Team Rocket, a criminal organization originally from Kanto. The player will also encounter Kimono Girls throughout the game. After battling all of them in a row, the player will be allowed to encounter a legendary bird specific to the game: Ho-Oh in HeartGold, and Lugia in SoulSilver. Both can be obtained in the games, however, the second one, i.e. Lugia in HeartGold and Ho-Oh in SoulSilver, can be obtained later on.

Still, there are some Pokémon specific in each game, such as in SoulSilver, the player can only capture Groudon, whereas in HeartGold, the layer can only capture Kyoger. A list of Pokémon featured in each game:

Image Courtesy: serebii.net