Notable differences exist between them. For instance, .Net Core is open-source and works great with different operating systems. .Net Framework, on the other hand, only works with Windows-based applications and is a close source. Comparing the performance between the two, .Net Core delivers better thanks to its modular architecture, whereas .Net framework is slow compared to the former. .Net Core does not feature code access security which is a bummer for application security, whereas .Net Framework has this feature available which is a huge plus point.