Similarities might include the main plot points and the overall world-building. Differences could come in the form of animation quality, soundtrack, and sometimes even the endings. Like, the manga might have a more open-ended conclusion while the anime might wrap things up more neatly.
Start with simple shapes and exaggerate the features. Focus on the most distinct characteristics of the person or thing you're drawing. Practice a lot and you'll get better at it.
There's 'YYY' manga that has yandere girls. Their popularity lies in the thrill and drama they bring to the story. They keep readers on the edge of their seats with their extreme emotions and actions.