Please advise

Staring at a book I was entering on a web page, I realised that my brain had recognised that there was a spelling mistake on the cover: Practicing Peace ought to be Practising Peace. Knowing it, and yet having to double check (because surely the author/editor/publisher would have checked?), I found a page with grammatical information, which noted that Advice and advise work the same way as practice and practise. The -ce form is the noun and the -se form is the verb. I've never connected the two/four words before.

Why is it that people rarely mix up to advise and advice, but often mix up to practise and practice, then? Interesting.

Edited to add: My son says it is simply the fact that the sound of advice and advise is different and the sound of practice and practise is the same. This raises a lot of questions I am interested in, about why I had never connected the two in my head before, as it offers an easy way to remember which spelling is appropriate for practice and practise. It indicates why English is such a nightmare for people to learn, when practice and practise sound the same and advice and advise do not. And makes me wonder again whether people are right to draw instant conclusions about people based upon how they speak or how they spell.