This game has seen a few different versions since its original 1991 release:

Game Boy
(Japan)

Japan was the first country to receive the game, under the name of Dracula Densetsu II (Legend of Dracula II). It was released on the 12th of July, 1991. This version features the holy water and cross as subweapons.

Game Boy
(America & Europe)

The next version of the game would be available in America, released on the 9th of August, 1991. The title screen was changed, featuring a new logo (and sadly losing the background castle and moon graphics). The intro, cutscene and ending text were translated into English. The sound test's track names were also altered, and given generic BGM # instead of the actual names featured in the Japanese version. And finally, the biggest change is that the cross subweapon was removed, and replaced with the battle axe. Exactly why this was done is unknown, I haven't been able to find any mention of it anywhere regarding this change. Perhaps the cross was seen as being a bit too religious for Nintendo? But then other Castlevania games for the NES had the cross in them.

This version would also be released in Europe, but it wouldn't be released there until the 26th of November 1992.

Game Boy
(Japan)

February 19th, 1998 saw the game's first re-release. Included on Konami GB Collection Vol. 3, this version is the same as the original other than the title screen having an updated copyright year and removing the Nintendo licensing text. The collection's intro features a small scene showing pixel art based on the Japanese version's original box art, and also has a typical typo (Dracura). An extremely short extract from the Crystal Castle theme plays during this. This version also has Super Game Boy support, featuring a new image of Christopher Belmont, alongside a big bat.

This version also features a character from Tokimeki Memorial, and there is a extra mode on the main menu where she can give you advice about each game on the collection.

Game Boy Color
(Europe)

The game was included on Konami GB Collection Vol. 4, which was released in Europe on the 26th of July, 2000. This version adds full color to the game if you play it on a Game Boy Color, although it also works on an original Game Boy system. It features the same intro as the Japanese collection version, although the title was changed to "Belmont's Revenge". The Super Game Boy support featured in the Japanese collection version was removed, along with the Tokimeki Memorial character and advice mode. The game's title screen was updated, strangely removing all text regarding the copyright year and Nintendo licensing. The cross weapon was kept in this version, in favor of the axe.

The biggest change for this version is that is features a new English translation -the text for the intro, cutscenes and ending were changed and given a new font. Soleiyu's name was changed to "Soleil", which is actually what the correct spelling should have been in the first place. For a full list of changeds made to the dialogue, click here. The sound test also lists the tracks with their original Japanese names, rather than the generic titles the 1992 European release featured.