People use the words interchangeably and then ask me why one class left them calm and the other left them rattled.
Restorative removes effort
The whole design is to hold you in a shape with enough support that your muscles have nothing to do. Bolsters, blankets, a wall, whatever it takes. If you are working, it is not doing its job.
Positions are held for a long time, but the long hold is not the stress, it is the delivery mechanism. Nothing should be intense. If something aches, the answer is more support, not more patience.
Yin applies load on purpose
Yin also holds for minutes at a time, and it deliberately takes you to a place where you can feel it. The target is connective tissue rather than muscle, and connective tissue only responds to sustained, unexciting load.
That means a yin pose is supposed to be somewhat uncomfortable and you are supposed to stay anyway. It is a completely different instruction from the one restorative gives you.
Why the mix-up matters
Someone who is exhausted and books yin because they wanted rest gets three minutes into a hip position with nowhere to go and has a hard time.
Someone who wants to work on stiff hips and books restorative spends an hour being comfortable and leaves feeling nothing changed, which is correct, because nothing was supposed to.
Both are good classes. I teach them as answers to different questions, and it is worth knowing which question you are asking.
Which to pick
If you are depleted, ill, injured or have slept badly, restorative. If you are functional and stiff and prepared to be bored and slightly uncomfortable, yin.
The one rule for both
Neither is a stretch class where more is better. In restorative, more support is better. In yin, less intensity held longer beats more intensity abandoned after a minute.
Time is doing the work in both. Your job is mostly to stay put and stop negotiating.