The idea of asexuality is nothing new to modern society. That’s not to say that everybody knows what it means and understands its intricacies, but it’s not a word that’s unheard of and a lot of people can work out what it means.
Aromanticism is newer and while it might sound similar, it is markedly different and the two terms are far from interchangeable. And while some people are both asexual and aromantic, many – including me – are aromantic without being asexual.
This video from Queer Ramblings goes into it really well.