In short, Dynamics 365 Business Central is an updated version of Dynamics NAV. Moreover, The Dynamics NAV version was powered by C/Al code, while the latest version (Dynamics 365 Business Central) is powered by AL code.
After that, Microsoft has crafted a modern and intuitive look & feel for the new version. Therefore, The users can now enjoy an interactive experience over the platform with well-placed key highlights. Meanwhile, the core functionality and features remain the same as Dynamics NAV.