Radicals are components that are specifically used for character indexing. There are around 200 radicals that are commonly used, and the 500+ components that HanziHero has includes all of those.
The HanziHero application makes no distinction between radicals and components. This is because a radical is simply a component that is used, somewhat arbitrarily, for character indexing. In other words, a radical is a component that is a bit more commonly used or recognized than other components. That’s all.
For example, the radical for 好 hǎo is 女 woman. If we wanted to look up that character in a Chinese dictionary, it would be listed under the 女 woman radical. It is similar to how we look up “apple” under “a” in an English dictionary.
This arbitrary but standardized set of character radicals are also called Kangxi radicals.
HanziHero has hundreds of components, and includes all of the standard radicals as well. If for some reason you were worried as to whether you were learning all of the radicals, rest assured that the HanziHero application will teach you all of them, as well as many other components (including some we have made ourselves).
Remember, the purpose of radicals and components are to help you learn and understand characters. They aren’t that important in themselves per se for reaching fluency. Even if they are pretty interesting.