The term “IDE” comes from Integrated Development Environment. It is intended as a set of tools that all work together: text editor, compiler, build or make integration, debugging, etc. Virtually all IDEs are tied specifically to a language or framework or tightly collected set of languages or frameworks. Some examples: Visual Studio for .NET and other Microsoft languages, RubyMine for Ruby, IntelliJ for Java, XCode for Apple technologies.
An editor is simply that, a tool that is designed to edit text. Typically they are optimized for programming languages though many programmer’s text editors are branching out and adding features for non-programming text like Markdown or Org Mode. The key here is that text editors are designed to work with whatever language or framework you choose.
The tradeoff here is that while you can generally get off the ground faster if you’re working within the realm of a given IDE, over the long term you spend a bunch of time retraining yourself when you inevitably change from one language or toolchain to the next. If you use an editor, you can continue to use the same workflows that you always have. Tools that you’ve built into your editor can be carried over to the next language and framework. Your editor becomes more powerful and more customized to how you want to work not just over years but potentially decades. Just ask people who use vim or Emacs … both of which have been available for over 25 years!
So, if you want something that you can just jump into and be productive right away in a specific technology, perhaps an IDE is what you’re looking for. If you want a tool that you can shape and customize into exactly what you want out of it even if it costs you some time up front configuring things, then an editor is probably more your speed