Which are more demanding EE or CS ?

This question has been discussed at length on Quora. But having been on the faculty of both the ECE and CS departments at CMU, and having degrees in both those fields, I feel well qualified to finally briefly enter into this discussion.

IMHO, ECE/CE is more difficult than CS (I assume you mean at the undergraduate level). I’ll add to Dan Ho’s answer.

There is a significant difference between “science” and “engineering” although knowledgeable people debate about the details of the difference. It has an impact on one’s mindset as well as on what one does in science vs. engineering. This is worth reading a bit about.

Although there is an overlap between CS and CE curricula (depending on the specific departments), each field has topics and prerequisites (and mindsets) the other doesn’t.

There is no question that CE is more “physical” than CS. Both CS and CE students like to build things, but many of the things CE students build are hands-on construction of and and experimentation with electronic devices; a minority of CS students build physical devices. Many incoming CE students have been electrical/electronic hobbyists since childhood. Increasingly, incoming students in both CE and CS have done a little “coding,” the relevance of which is subject to debate. Software is mostly a tool in CE vs. also being a topic of understanding and research in CS.

There is also no question that various CE undergrad (and of course grad) courses require more advanced mathematics than is found in CS courses (except some theory courses, which require an entirely different kind of mathematics).

So, in short, it is my experience and judgement that for most people, ECE/CE is more difficult than is CS.