I have seen screens of Ninja Gaiden Black and some of the maps looks exactly like Ninja Gaiden Nr.1

is it the same just as a new version?

Its the same with:
Compatible with Xbox™ Live: Karma scores can be uploaded to the online leader boards via Xbox Live

Increased Levels of Difficulty: Five levels of difficulty for all kinds of gamers including "Ninja Dog" to "Very Difficult Master Ninja"

Increased Action-Packed Missions: Play in Story mode or Mission Mode with a massive number of missions to complete, including traditional enemy battles, time challenges, boss battles and more!

Challenging Hurricane Packs Content: Content such as new enemies and big, bad bosses from Hurricane Packs 1&2 included as special bonus for an extra ninja challenge.

Never-Before-Seen Content: New cinematic cut scenes that reveal secrets from the world of Ninja Gaiden.

Jaw-dropping Sounds and Graphics: Stunning graphics and incredible sounds as you would expect from Tecmo’s esteemed development team, Team NINJA

Colossal Amounts of Bonus Content: Hidden unlockables including the original arcade version of Ninja Gaiden, Ninja Ryukenden, available for the first time on a video game console in Ninja Gaiden: BLACK

Yes. It just has all the online updates for the people who don't have Xbox Live.

It also includes few new cutscens and new and better AI.