Despite being a manga adaptation of the anime the story follows the same beats, but it's drastically different. Which isn't a bad thing at all since it makes the manga it own thing to enjoy if you already love the original anime.
Being only 5 volumes long there were some events in the anime that were changed or taken out of the manga. Some events got replaced with manga only events and some characters were removed from the story and/or replaced. So the manga kinda the same as the anime, but not really.
The story is really good and the art is amazing. Some of the changes may suit you better, if you didn't like how certain things happened within the anime's story. I will admit since I read the physical volumes the translation is a little off and there are even some spelling mistakes. It's not so bad, but if things like that bother just read the manga online.
Despite the translation errors and misspelling this manga is a really good read! I would even recommend it to the people who are too intimidated to watch the 50 episode anime.
If you're already a Blood+ fan I highly reommend this manga, especially if you want more content from the story. If you never experienced Blood+ and don't want to watch all 50 episodes of the anime, then this manga is a good substitute.