I googled but found nothing satisfactory. What’s their difference? What’s the situation respectively to use one over the other?
In addition to the things allready said here:
If you group layers together they have to stay together. There is no way to ungroup a layer between two grouped layers. You can do this with linked layers.
Here is one case I use linked layers for:
When I am creating an new website layout and want it to have some fixed parts and some parts, that are scrolling along the side, I can link the scrolling parts together.
Usually I organize my layout in groups to collapse the parts I don’t need and don’t get overwhelmed by hundreds of layers. The basic groups could be Header, Content, Navigation, Sidebar and Footer. Lets say I want the header, the navigation and the footer to stay fixed, while the sidebar scrolls along the content, without loosing its relative position.
To group those elements together I would have to reorder my layergroups, but I can link them no matter what the order is. Now I can scroll my content and the sidebar will keep its relative position to the footer.
Layergroups do have a whole range of other purposes, but to list all the functions of layergroups is not the topic here, I think.
Source : Link , Question Author : Philip007 , Answer Author : Afterlame