OK are Manga and Anime very different?
Er, yes. Manga are comics, graphic novels, usually drawn in black and white and read from the back to the front, from right to left, as that's how the original Japanese is printed. Visit the scifi/ fantasy section of your nearest Waterstones, or the manga section of Forbidden Planet/Traveling Man etc to have a look through. Popular manga for the KS3 crowd are things like Naruto, Fairy Tail, and Magical X Miracle (these are all on my dd's shelf and she first got them from the school library). There's also sports-based manga such as Karate Heat.
Anime is, unsurprisingly, animated material either in short cartoon form or longer films - you may have come across Studio Ghibli films, for example. I'm quite fond of the Chi cartoons which are on Amazon Prime (it's about a cute kitten and her family and has English subtitles).
There is crossover, which causes confusion but actually it's no different from Marvel comics becoming films and cartoons: there are often manga comics of film/tv series, and anime of stories which started as manga. Sailor Moon is probably the most widely known. Video games straddle all three media - Pokémon being probably the best known example of a behemoth of all media!
The industry is vast, and like Hollywood, it's not all suitable for kids. There are frequently age ratings on manga and anime just like there are on Western comics and films. It is, as ever, media in the wilds of YouTube you need to be wary of.