Magento 2.0 vs Magento 1.x
Recently with the launch of Magento 2.0, eCommerce platforms development is totally revolutionized. Magento 2.0 filled the compatibility issues which Magento's old version had. Now Magento's latest version is compatible with Popular platforms like Oracle and MSSQL. Magento 2.x also easily supports HTML5.
Earlier there was no facility to manage dependencies, but now Magento 2.x uses composer for this purpose.
Also, automated testing was introduced in the latest version. Using the Magento Testing Framework, users can create and run functional tests like smoke testing, regression testing, etc.
Magento 2.x Service contracts instead of API (Application Programming Interface)
Writing code efficiently increases the site's execution and decreases the loading time. Configuration of the server of large-scale sites is also important to enhance web traffic.
Speeding up Webpage
To speed up the web page, Magento 2.x introduced built-in full page caching. For Magento 1.x there needed to install an external module for it.
Magento 2.x also comes with built-in features like Return Merchandize Authorization (RMA), advanced customer segmentation (to divide the marketplace into parts), gift registry, and better performance PCI (Payment Card Industry).
Magento 2.x is established on Magento Framework and other PHP frameworks like Symfony while Magento 1.x was based on Zend framework only.
Jquery vs PrototypeJS
Magento 2.x is based on jQuery whereas Magento 1.x extensively used PrototypeJS. jQuery has a larger community as compared to PrototypeJS, it provides more support, and has solutions for all of the developers' questions.
Magento 2.x architecture
Magento 2.x architecture is component-oriented. If there is no need for any module the admin can disable it without worrying about affecting the functionality of other modules.