Since HeartGold and SoulSilver are part of the same pair of games, there are only a handful of differences between them, though probably the most noticeable are the version-exclusive Pokémon.
It's all a matter of personal preference.
http://bulbapedia.bulbagarden.net/wiki/Pokémon_HeartGold_and_SoulSilver_Versions
Well Exclusive Pokemon for Heart Gold are Mankey, Primape, Growlithe, Arcanine, Spinarak, Ariados, Gligar, Mantine, Phanpy, Donphan, Sabelye, Baltoy, Claydol, Kyorge, Mantyke and Gliscor.
Exclusive Pokemon For Soul Silver are Vulpix, Ninetales, Meowth, Persian, Ladiba, Ledian, Teddiursa, Ursaring, Delibird, Scarmory, Mawile, Gulpin, Swalot and Groudon.
There You Go! =D
The card key in Pokemon Heartgold and Soulsilver is located in the Goldenrod Underground.
The Quick claw is located in the National Park in Pokemon Heartgold and Soulsilver.
You can't. You need to get Heatran from Pokemon Diamond, Pearl and Platinum and then trade to heartgold and soulsilver.
In HeartGold and SoulSilver, she does not battle you - which might be one of the reasons why she doesn't have a starter pokemon. Instead, she has a Marill.
The only way to get a gligar in pokemon soulsilver is to trade with pokemon heartgold.
SOulsilver
Pokemon Heartgold and Soulsilver are the remakes of the old Pokemon Gold, Silver, and Crystal series. Pokemon Heartgold and Soulsilver are for the Nintendo DS.
The hoothoot is better
No, there are no underwater routes in Pokemon HeartGold or SoulSilver. The HM Dive is not available in Pokemon HeartGold or SoulSilver.
he is not in Pokemon soulsilver or Pokemon heartgold
That is impossible in Pokemon HeartGold and SoulSilver.
You can only go to Johto and Kanto in Pokemon Heartgold and Soulsilver
Pokemon Soulsilver and Heartgold cost about 35 to 40 dollars on the US
The card key in Pokemon Heartgold and Soulsilver is located in the Goldenrod Underground.
The Quick claw is located in the National Park in Pokemon Heartgold and Soulsilver.
You can't. You need to get Heatran from Pokemon Diamond, Pearl and Platinum and then trade to heartgold and soulsilver.
Well, both are about the same, but the best is probably your mother.