Both Reactjs and React Native are essential for app and web development, and due to their functionalities, they are evolving around the globe in technology. 

While Reactjs is a JavaScript library and React Native is the whole framework, the former is the part of the latter, and both compliments each other.

If Reactjs is optimal for creating apps with high functionality and complex calculations, then React Native is ideal to give a native feeling to your mobile apps.

Every technology or framework has some shortcomings, and so does Reactjs and React Native have. 

• Reactjs can be described as a base derivative of React DOM, for the web platform while React Native is a base derivative in itself, which means that the syntax and workflow remain the same, but components alter.
  
• Reactjs, eventually, is a JavaScript library, which allows the programmer to create an appealing and high performing UI Layer while React Native is an entire framework for developing cross-platform apps, be it web, iOS or Android. 
  
• In Reactjs, virtual DOM is used to render browser code in Reactjs while in React Native, native APIs are used to render components in mobile.
  
• The apps developed using  Reactjs renders HTML in UI while React Native uses JSX for rendering UI, which is nothing but javascript. 
  
• CSS is used for creating styling in Reactjs while a stylesheet is used for styling in React Native.
  
• In Reactjs, the animation is a thing, using CSS, just like web development while in React Native, an animated API is used for producing animation across different elements of the React Native application.
  
• If the need is to build a high performing, dynamic, and responsive UI for web interfaces, then Reactjs is the best option while if the need is to give mobile apps a truly native feeling, then React Native is the best choice.