Yes. 5 has some significant differences from 4 (being based on a completely different program), and when it was released it was missing some key features from 4, but over time and a few updates, almost all of those have been added back in. 5 is more robust and has far better brush customization. Even if you’ve mastered 4, 5 will take a little getting used to, but I can’t imagine going back now.
The EX version does have a few features not included in the regular version (full list found here). For me, the big one is the ability to create Story Files, which is just a way to organize and collect a lot of separate pages (I make a big blank story file with hundreds of pages and use it as a digital sketchbook).
All the drawing tools are present in the standard version. EX is useful if you’re working on multiple-page stories, but even then it’s not necessary (just very helpful).